ui: call-display: set speaker and mute buttons sensitive by default

Now that we got rid of ugly hacks, these buttons should work on all
devices. We can therefore enable them by default.

src/ui/call-display.ui

@@ -100,7 +100,7 @@
                             <property name="receives_default">True</property>
                             <property name="no_show_all">True</property>
                             <property name="hexpand">True</property>
-                            <property name="sensitive">False</property>
+                            <property name="sensitive">True</property>
                             <signal name="toggled" handler="mute_toggled_cb" swapped="no"/>
                             <child>
                               <object class="GtkBox">
@@ -137,7 +137,7 @@
                             <property name="receives_default">True</property>
                             <property name="no_show_all">True</property>
                             <property name="hexpand">True</property>
-                            <property name="sensitive">False</property>
+                            <property name="sensitive">True</property>
                             <signal name="toggled" handler="speaker_toggled_cb" swapped="no"/>
                             <child>
                               <object class="GtkBox">