video: msm: Add Histogram collection framework for MDP blocks

Expand the previous histogram collection implementation to support the
addition of other MDP blocks that allow for histogram data collection.
Support the VG1, VG2, DMA-P, and DMA-S histograms using this new
framework (VG pipes only supplying the histogram of luminance).

Change-Id: I94088c1f714fa5d91256ae7b0f5548f8a0b81763
Signed-off-by: Carl Vanderlip <carlv@codeaurora.org>