ARM: EXYNOS4: Moved board support files

This patch moves board support files, SMDKC210, SMKDV310
and UNIVERSAL_C210 into arch/arm/mach-exynos4/ according
to the change of ARCH name, EXYNOS4.

Cc: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>