ARM: SAMSUNG: fix suspend/resume on if some GPIO banks not present

When saving GPIOs during suspend/resume we need skip missing GPIO banks, not
trying get corresponding chip again and again in infinite loop.

Signed-off-by: Jiri Pinkava <jiri.pinkava@vscht.cz>
[ben-linux@fluff.org: shorten subject]
Signed-off-by: Ben Dooks <ben-linux@fluff.org>