pinctrl: samsung: removing duplicated condition for PINCTRL_SAMSUNG

Now, PINCTRL_SAMSUNG should be enabled with PINCTRL_EXYNOS so we don't
need to add 'depends on' condition already added in PINCTRL_EXYNOS.

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