msm: mdss: Support ARGB1555 and ARGB4444

Add support for  ARGB1555 and ARGB4444 formats in
mdp.

Change-Id: I6000316d177d9988eabcca8f43131e3a9f636961
Signed-off-by: Vishnuvardhan Prodduturi <vproddut@codeaurora.org>