The scatterlist traversal is made proper. The patch has some minor comments
modification and also sets the value written to the DAVINCI_MMCTOR register
properly. The timeout calculation is made proper by deriving it from the
clock values.

This patch incorporates most of review comments given on LKLM by
Pierre Ossman.
Signed-off-by: Vipin Bhandari <vipin.bhandari@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>