video: s3c-fb: add window variant information for S5P

Compared to s3c64xx, S5P series such as S5PC100 and S5PV210 have
the different window features including valid bpp, palette size
and palette bpp. Therefore, window variant information for S5P
should be added.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>