msm: mdss: refactor overlay parameters validation

Some checks done on parameters don't apply for rotation only mode where
rotation is not limited by the bounds of panel resolution. Update
overlay checks to perform correct validation depending on request type.

Change-Id: Ic0cf9863231300f7190dd118b78fa753f77f217f
Signed-off-by: Adrian Salido-Moreno <adrianm@codeaurora.org>