modem: move GetInfo from GsmCard -> Modem interface

It's generic, everything implements some variant of +GMM, +GMR, and +GMI.

introspection/mm-modem-gsm-card.xml

@@ -28,19 +28,6 @@
       </arg>
     </method>
 
-    <method name="GetInfo">
-      <tp:docstring>
-	Get the card information (manufacturer, modem, version).
-      </tp:docstring>
-      <annotation name="org.freedesktop.DBus.GLib.Async" value=""/>
-      <annotation name="org.freedesktop.DBus.GLib.CSymbol" value="impl_gsm_modem_get_info"/>
-      <arg name="info" type="(sss)" direction="out">
-	<tp:docstring>
-	  Structure containing manufacturer, model, and version (revision) of the card.
-	</tp:docstring>
-      </arg>
-    </method>
-
     <method name="SendPuk">
       <tp:docstring>
 	Send the PUK and a new PIN to unlock the SIM card.

introspection/mm-modem.xml

@@ -49,6 +49,19 @@
       </arg>
     </method>
 
+    <method name="GetInfo">
+      <tp:docstring>
+        Get the card information (manufacturer, modem, version).
+      </tp:docstring>
+      <annotation name="org.freedesktop.DBus.GLib.Async" value=""/>
+      <annotation name="org.freedesktop.DBus.GLib.CSymbol" value="impl_modem_get_info"/>
+      <arg name="info" type="(sss)" direction="out">
+        <tp:docstring>
+          Structure containing manufacturer, model, and version (revision) of the card.
+        </tp:docstring>
+      </arg>
+    </method>
+
     <property name="Device" type="s" access="read">
       <tp:docstring>
 	The modem port to use for IP configuration and traffic.