platform/x86: fujitsu-laptop: add and remove platform device in separate functions

Platform device handling adds a lot of complexity to fujitsu_init(),
which hinders its readability.  Extract code responsible for adding and
removing the platform device to separate functions.  Adjust whitespace
to make checkpatch happy.

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