msm: mdss: Fix case of pack pattern being 0 in mdp3

The pack pattern in mdp3 should never be 0. This pack pattern
is read by userspace using sysfs node. If found zero there
might be error in computation logic used for calculation of
CSC registers. This may cause adverse effects such as black
screen, hence the pack pattern exposed should be non zero
and valid.

Change-Id: I9d3a13f3ff3d932a6b62cf2f5715e6b18a6834e5
Signed-off-by: Krishna Chaitanya Parimi <cparimi@codeaurora.org>