GPIO: vt8500: Add extended gpio bank for WM8505/WM8650

These SoC's have an extended bank of GPIO's seperate to the main
GPIO block. This patch adds the additional 5 GPIO's located in this
block which control I2C and PWMOUT.

Signed-off-by: Tony Prisk <linux@prisktech.co.nz>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>