defaults: Don't rotate screen on orientation changes

With phosh!434
we listen to the sensor but don't want to do that by default
to preserve current behavior and since landscape often isn't useful.

The phosh's quicksettings toggles this setting.

default/11_librem5.gschema.override

@@ -21,6 +21,9 @@ picture-uri='file:///usr/share/librem5/default-theme/adwaita-phone.jpg'
 [org.gnome.desktop.sound]
 theme-name='librem5'
 
+[org.gnome.settings-daemon.peripherals.touchscreen]
+orientation-lock=true
+
 [org.gnome.settings-daemon.plugins.wwan]
 unlock-sim=true