revent NFE in SystemUI when parsing invalid int (2)

A user can change various tunable settings setting via adb.

If the value set is not an integer, SystemUI will end up in an exception
loop.

Test: No crash when running:
      adb exec-out settings put secure sysui_qs_move_whole_rows a
      adb exec-out settings put secure qs_show_brightness a
      adb exec-out settings put secure clock_seconds a
      adb exec-out settings put secure sysui_volume_down_silent a
      adb exec-out settings put secure sysui_volume_up_silent a
      adb exec-out settings put secure sysui_do_not_disturb a
Change-Id: If9c565cbdd44db25ba7fce381c98aa0ab735bfc4