platform/x86: fujitsu-laptop: update debug message logged by call_fext_func()

Update debug message logged when the acpi_evaluate_integer() call inside
call_fext_func() fails so that it covers a broader set of possible
errors.

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