Vertical sync height register can only hold 6 bits.  Fix the hsync start test
to use > instead of >=.  Also add a few clarifying comments.
Signed-off-by: NVille Syrjala <syrjala@sci.fi>
Acked-by: NBen Dooks <ben-linux@fluff.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>