ARM: shmobile: move custom gpio functions to sh-gpio.h

Move custom shmobile gpio code to a sh-gpio.h to remove the dependency
on mach/gpio.h. shmobile always uses gpiolib, so we can remove
__GPIOLIB_COMPLEX define from mach/gpio.h.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Magnus Damm <magnus.damm@gmail.com>