mach-ux500: board support for AB8500 GPIO driver

This is the board support patch for ab8500 gpio driver
on mach-ux500.Patch implements 16 virtual
IRQ mapped to 16 interrupt capable AB8500 GPIOs.

Signed-off-by: Bibek Basu <bibek.basu@stericsson.com>
[Modify for header file placement]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>