gpio: fix a build failure on KS8695 GPIO

I screwed up by compiling that driver for the machine rather
than the arch. Correcting this fixes the build error.

Cc: Grant Likely <grant.likely@secretlab.ca>
Reported-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>