pinctrl: exynos: Set pin function to EINT in irq_set_type of GPIO EINTa

Pins used as GPIO interrupts need to be configured as EINTs. This patch
adds the required configuration code to exynos_gpio_irq_set_type,
to set the pin as EINT when its interrupt trigger is configured.

Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>