msm: mdss: add LP/HS mode DCS CMD support to MDP5 targets

LP/HS mode configuration for DCS Commands in currently not
supported on MDP5 targets. Add the required support to meet
all panel requirements.

Change-Id: Ib31ddc02f151033a59d6297c8f1a4f8897378947
Signed-off-by: Shuo Yan <shuoy@codeaurora.org>