ARM: EXYNOS: Move G2D clock entries to clock-exynos4210.c file

G2D clock registers are different in EXYNOS4210 and EXYNOS4X12 SoCs.
Hence moving the SoC specific G2D clock entries from common clock file
(clock-exynos4.c) to EXYNOS4210 specific clock file (clock-exynos4210.c).

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>