platform/x86: fujitsu-laptop: clean up local variables in call_fext_func()

Set values of FUNC call parameters in a designated initializer.  Do not
initialize status and handle variables as the values these are
initialized to have no influence on execution flow.  Use an array
variable instead of the address of the first element of that array.

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