disp: msm: dsi: make panel commands async for vid to cmd switch

Optimize pre mode switch panel command by transferring async. This
removes the time waited until subsequent dma_done irq.

Change-Id: I2e2516fdd641e85d1f1b221a6ea7999c868edf00
Signed-off-by: Nilaan Gunabalachandran <ngunabal@codeaurora.org>