msm: mdss: Add six zone LUT size as PAv2 parameter

Added six zone LUT size as a parameter to PAv2 in order for the size to be
specified by the user. This size is sanitized based on the required LUT
size.

Change-Id: Iaf1b418ce1a3ec4b5013b1192c7f3b7de5827e3d
Signed-off-by: Benet Clark <benetc@codeaurora.org>