disp: msm: dsi: trigger broadcast commands using DMA start window

As per the HW requirements it is highly recommended to use DMA start
window to trigger  broadcast commands. If not used then it can
result in a hardware hang with the DSI controllers going out
of sync. This behavior is even more prominent in cases of higher
refresh rates. As part of the change we change the default DMA
scheduling behavior to default to maximum possible DMA window
in case it is not specified in the panel device tree.

Change-Id: Ied4df9063664cedbc18ce009054d4e5ecae30ab2
Signed-off-by: Satya Rama Aditya Pinapala <psraditya30@codeaurora.org>