platform/x86: fujitsu-laptop: Defer input device registration

Only register input devices after the device-specific data structures
they access are fully initialized.

Signed-off-by: Michał Kępień <kernel@kempniu.pl>
Reviewed-by: Jonathan Woithe <jwoithe@just42.net>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>