drm/msm/sde: CCN Cleanup for sde_kms

Add changes in the sde kms to reduce
Cyclomatic Complexity Number to less than thirty
for more readable, less complex code.

Change-Id: I36619e61789de6cb238b5355839069a87b1bbe81
Signed-off-by: Nilaan Gunabalachandran <ngunabal@codeaurora.org>