mfd: PCF50633 gpio support

What the PCF05633 calls as a 'GPIO' is much more than the GPIO in the linux
sense and there are only 4 of them - which means, the gpiolib is not used
here.

Signed-off-by: Balaji Rao <balajirrao@openmoko.org>
Cc: Andy Green <andy@openmoko.com>
Signed-off-by: Samuel Ortiz <sameo@openedhand.com>