pinctrl: exynos5440: add pinctrl driver for Samsung EXYNOS5440 SoC

Add a new pinctrl driver for Samsung EXYNOS5440 SoC. The pin controller
module in EXYNOS5440 is different from the pin controller found on other
Samsung SoC. Hence, the pin controller driver for EXYNOS5440 SoC is
independent of the Samsung pinctrl framework.

Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>