[ARM] 3160/1: SharpSL: Add driver for Akita specific GPIOs

Patch from Richard Purdie

Add a driver for the extra GPIOs found on the Sharp SL-C1000 (Akita).
These GPIOs are found on a Maxim MAX7310 I2C i/o expander chip. A
generic GPIO driver for the MAX7310 was attempted but this mini
driver is a much simpler and much more effective solution avoiding
several issues and complexity the generic driver had (as discussed
on LKML).

The platform device is required so the device parent can be set
correctly which ensures the device is one of the last to suspend
and first to resume. Whilst the i2c suspend/resume calls can be
influenced, nothing guarantees this is easlier/later than the
subsystems the gpios are used on which are all independent of i2c
(sound, irda, video/backlight etc.).

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>