pinctrl/nomadik: add hsit_a_2 pin group

On 8500 and 9540, all HSI pins are driven by HSI block except
HSIT_ACWAKE0_a which is driven as GPIO due to specific
constraints. A new group hsit_a_2 is created which exclude
HSIT_ACWAKE0_a pin.

Signed-off-by: Patrice Chotard <patrice.chotard@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>