msm_fb: Make sure BLT is enabled on DMA_S.

Some cases like recovery are not using DMA_S pipe. This is fine as long as we're
not running to color configuration issues.

Always enable BLT mode to let overlay mixer produce the image for DMA_S.

Change-Id: I270b53375147772693be4ee9101bbca1559a29fa
msm_fb: Sync DMA_S config with DMA_P.

Change-Id: I5be2d32777dd408b75dc8a2a44b8d408f97a83c5
msm_fb: Send vSync events properly.

Following MDSS changes, vSync events should be terminated.

Change-Id: Ib758efde02fe708a33bc6c719e3d5f5a6ed4a386