msm: mdss: Use YCrCb 420 as the output format for writeback
msm: mdss: Use YCrCb 420 as the output format for writeback

Use YCrCb 420 (NV12) as the output format for writeback.  For Wifi Display
use case, NV12 is required as the encoder requires this as the output
format.

Change-Id: Ica8851073476b9c05f3b5b41232803c2d71f7a3e
Signed-off-by: Deva Ramasubramanian <8f8b6109cd5e7b75746932bf5dcf69e763e1f0b2@codeaurora.org>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas