msm: mdp3: underflow color adjust support on 8x10

This adds the underflow color adjustment support on
8x10. Customer can order underflow color by modifying
the parameter in panel device tree.

Change-Id: I5a0ae73bceff26b810de6809beb540681c30247f
Signed-off-by: Shuo Yan <shuoy@codeaurora.org>