api,dbus: fix SignalQuality property signature so that it's a (ub) tuple

new/org.freedesktop.ModemManager1.Modem.xml

@@ -10,7 +10,7 @@
 	Enable or disables the modem.  When enabled, the modem's radio is powered
 	on and data sessions, voice calls, location services, and Short Message
 	Service may be available.  When disabled, the modem enters low-power
-	state and no network-related operations are available. 
+	state and no network-related operations are available.
       </tp:docstring>
       <annotation name="org.freedesktop.DBus.GLib.Async" value=""/>
       <annotation name="org.freedesktop.DBus.GLib.CSymbol" value="impl_modem_enable"/>
@@ -49,7 +49,7 @@
 	  properties are only applicable to a bearer of certain access
 	  technologies, for example the "apn" property is not applicable to
 	  CDMA2000 Packet Data Session bearers.  Allowed properties are:
-	  
+
 	     apn      : (3GPP, required) Access Point Name
 	     ip-type  : (3GPP and CMDA, optional) Addressing type, one of
 	                "IPV4", "IPV4V6", or "IPV6"
@@ -193,7 +193,7 @@
     <property name="MaxActiveBearers" type="u" access="read">
       <tp:docstring>
         The maximum number of active packet data bearers the modem supports.
-        POTS and CDMA2000-only devices support one active bearer, while 
+        POTS and CDMA2000-only devices support one active bearer, while
         GSM/UMTS and LTE-capable devices (including LTE/CDMA devices) typically
         support at least two active bearers.
       </tp:docstring>
@@ -284,7 +284,7 @@
       </tp:docstring>
     </property>
 
-    <property name="SignalQuality" type="ub" access="read">
+    <property name="SignalQuality" type="(ub)" access="read">
       <tp:docstring>
         Signal quality in percent (0 - 100) of the dominant access technology
         the device is using to communicate with the network.  Always 0 for POTS