platform/x86: fujitsu-laptop: Unify local variable naming

Different functions in the module use varying names (error, result,
status) for a local variable storing the return value of a function call
that has to be checked for errors.  Use a common name (ret) for all
these local variables to improve code consistency.  Merge integer
variable declarations in acpi_fujitsu_laptop_add() into one line.

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