msm: mdss: fix MDP color format offsets

Color offsets are used by some X11 environments
to properly set/get the color format.

This change fixes the offsets to represent the color formats
correctly.

Change-Id: I5068897f18e1d119a9bb7f1fe59f9b662153e1b0
Signed-off-by: Eugene Yasman <eyasman@codeaurora.org>