gpio: samsung: Skip registration if pinctrl driver is present on EXYNOS4X12

This patch modifies the Samsung GPIO driver to check for pinctrl driver
presence earlier and use generic matching instead of a single compatible
value.

This allows us to fix warning about unrecognized SoC in case of
EXYNOS4X12, which is not supported by this driver.

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