serial: samsung: Add support for EXYNOS4212 and EXYNOS4412

This should be added for EXYNOS4212 and EXYNOS4412 SoCs.

Cc: Thomas Abraham <thomas.abraham@linaro.org>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>