msm: mdss: remove downscale overflow check for recent MDP revisions

The overflow check for downscaling was added due to bug in scaler for
earlier MDP revisions. The bug has been addressed in MDP 1.03 and newer
revisions, hence keep check only for older revisions.

Change-Id: I2df98f7d23c016472bc4bcf67ce37fba4fb2c40e
Signed-off-by: Adrian Salido-Moreno <adrianm@codeaurora.org>
Signed-off-by: Krishna Chaitanya Devarakonda <kdevarak@codeaurora.org>