platform/x86: fujitsu-laptop: use device-specific data in remaining module code

To avoid using module-wide data in remaining module code, employ
acpi_driver_data() and dev_get_drvdata() to fetch device-specific data
to work on in each function.  This makes the input local variables in
hotkey-related callbacks and the module-wide struct fujitsu_laptop
redundant, so remove them.  Adjust whitespace to make checkpatch happy.

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