video: s3c-fb: use ARCH_ dependancy

Use ARCH_ dependancy when using s3c-fb.  S3C_DEV_FB, S5P_DEV_FIMD0 cannot
be enabled on EXYNOS5.  So, ARCH_ should be used as dependancy for s3c-fb.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Tomasz Figa <t.figa@samsung.com>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>