msm_fb: Fix chroma offset calculation for YUV as source format

For frame composition using MDP, fix the calculation of source
chroma offset pointer to be programmed to MDP hardware whenever
the crop 'y' value is non-zero. This prevents green lines/chroma
shift and other artifacts from being seen on the panel.

CRs-fixed: 438027
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>
(cherry picked from commit 396e4abfd12cd1feeef71fddff5d6752ee136632)

Change-Id: I8b47d22d5d660d1c4fe6acd3ae2a5db9c6393e7c
Signed-off-by: Akhila Musunuri <makhila@codeaurora.org>