api,modem: improve capabilities related documentation

And remove the unused mm_common_build_capability_combinations_any()
method in the common non-public library code.

introspection/org.freedesktop.ModemManager1.Modem.xml

@@ -146,7 +146,12 @@
         SetCurrentCapabilities:
         @capabilities: Bitmask of <link linkend="MMModemCapability">MMModemCapability</link> values, to specify the capabilities to use.
 
-        Set the capabilities of the device. A restart of the modem may be required.
+        Set the capabilities of the device.
+
+        The given bitmask should be supported by the modem, as specified in the
+        #org.freedesktop.ModemManager1.Modem.Modem:SupportedCapabilities property.
+
+        This command may power-cycle the device.
     -->
     <method name="SetCurrentCapabilities">
       <arg name="capabilities" type="u" direction="in" />
@@ -230,12 +235,16 @@
         SupportedCapabilities:
 
         List of <link linkend="MMModemCapability">MMModemCapability</link>
-        values, specifying the combinations of generic family of access
+        bitmasks, specifying the combinations of generic family of access
         technologies the modem supports.
 
-        If the modem doesn't allow changing the current capabilities, a single entry with
+        If the modem doesn't allow changing the current capabilities, the
-        <link linkend="MM-MODEM-CAPABILITY-ANY:CAPS"><constant>MM_MODEM_CAPABILITY_ANY</constant></link>
+        list will report one single entry with the same bitmask as in
-        will be given.
+        #org.freedesktop.ModemManager1.Modem.Modem:CurrentCapabilities.
+
+        Only multimode devices implementing both 3GPP (GSM/UMTS/LTE/5GNR) and
+        3GPP2 (CDMA/EVDO) specs will report more than one combination of
+        capabilities.
     -->
     <property name="SupportedCapabilities" type="au" access="read" />
 
@@ -243,8 +252,11 @@
         CurrentCapabilities:
 
         Bitmask of <link linkend="MMModemCapability">MMModemCapability</link>
-        values, specifying the  generic family of access technologies the modem
+        values, specifying the currently used generic family of access
-        currently supports without a firmware reload or reinitialization.
+        technologies.
+
+        This bitmask will be one of the ones listed in
+        #org.freedesktop.ModemManager1.Modem.Modem:SupportedCapabilities.
     -->
     <property name="CurrentCapabilities" type="u" access="read" />
 

libmm-glib/mm-common-helpers.c

@@ -538,17 +538,6 @@ mm_common_build_capability_combinations_none (void)
     return g_variant_builder_end (&builder);
 }
 
-GVariant *
-mm_common_build_capability_combinations_any (void)
-{
-    GVariantBuilder builder;
-
-    g_variant_builder_init (&builder, G_VARIANT_TYPE ("au"));
-    g_variant_builder_add_value (&builder,
-                                 g_variant_new_uint32 (MM_MODEM_CAPABILITY_ANY));
-    return g_variant_builder_end (&builder);
-}
-
 void
 mm_common_get_bands_from_string (const gchar *str,
                                  MMModemBand **bands,

libmm-glib/mm-common-helpers.h

@@ -126,7 +126,6 @@ MMModemCapability *mm_common_capability_combinations_variant_to_array  (GVariant
 GVariant          *mm_common_capability_combinations_array_to_variant  (const MMModemCapability *capabilities,
                                                                         guint n_capabilities);
 GVariant          *mm_common_capability_combinations_garray_to_variant (GArray *array);
-GVariant          *mm_common_build_capability_combinations_any         (void);
 GVariant          *mm_common_build_capability_combinations_none        (void);
 
 GArray                              *mm_common_oma_pending_network_initiated_sessions_variant_to_garray (GVariant *variant);