msm: mdss: Support split mode configuration

For destination split panels driver should allow the client to enable
the post processing features for entire screen or one of the slpit
sides. Change adds support in post processing driver to allow the
clients to configure feature in split mode panels.

Change-Id: I2c84aa488205aaa17b5abd3bc26b975361967bba
Signed-off-by: Gopikrishnaiah Anandan <agopik@codeaurora.org>