sony-laptop: fix sparse non-ANSI function warning

Fix sparse warning for non-ANSI function declaration:

drivers/platform/x86/sony-laptop.c:1134:35: warning: non-ANSI function declaration of function 'sony_nc_rfkill_update'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc:	Matthew Garrett <mjg@redhat.com>
Cc:	Mattia Dongili <malattia@linux.it>
Signed-off-by: Matthew Garrett <mjg@redhat.com>