msm_fb: Provide support for ARGC and CSC for layer mixer 2

MDP 4.4 supports additional layer mixer (LM2) with ARGC and
CSC blocks. Extend existing ARGC and CSC functionality to additional
layer mixer (LM2).

Change-Id: Id9e5d0a80fcd9a6e3b6132b083d8a43450c0efa1
Signed-off-by: Pravin Tamkhane <pravint@codeaurora.org>

Conflicts:

	drivers/video/msm/mdp4_util.c