platform/x86: fujitsu-laptop: move keycode processing to separate functions

acpi_fujitsu_hotkey_notify() is pretty deeply nested, which hurts
readability.  Move the keycode processing part to two separate functions
to make the code easier to understand and save a few line breaks.
Rename variable keycode_r to keycode as there is no longer any need to
differentiate between the two.  Tweak indentations to make checkpatch
happy.

Signed-off-by: Michał Kępień <kernel@kempniu.pl>
Acked-by: Jonathan Woithe <jwoithe@just42.net>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>