ARM: pxa: zylonite: use gpio lookup instead mfp header

The mach/mfp.h header is only used by this one driver
for hardcoded gpio numbers. Change that to use a lookup
table instead.

Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: linux-input@vger.kernel.org
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>