video: s3c-fb: use FIMD_V8_VIDTCON0 for EXYNOS5 FIMD

This patch uses FIMD_V8_VIDTCON0 as the address definition
of VIDTCON0 register, because the address offset of VIDTCONx
registers is changed from 0x0 to 0x20000 for EXYNOS5 FIMD.
So, FIMD_V8_VIDTCON0 should be used.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>