Some systems may not support input events, or registering the input
handler may have failed. So check that an input device exists before
trying to set the docking and tablet mode state during resume.

Fixes: http://bugzilla.kernel.org/show_bug.cgi?id=13865Reported-and-tested-by: NCédric Godin <cedric@belbone.be>
Signed-off-by: NFrans Pop <elendil@planet.nl>
Acked-by: NMatthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: NLen Brown <len.brown@intel.com>