ARM: dts: exynos: Add initial gpio setting of MMC2 device for exynos3250-monk

This patch adds initial pin configuration of MMC2 device on exynos3250-monk
board because the MMC2 gpio pin (gpk2[0-6]) are NC (not connected) state.

Suggested-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>