msm: mdss: Add BTA status check API in DSI controller

Add Bus-Turn-Around (BTA) status check API in DSI
controller to check if it is alive or not. Subscriber
of this API should send relevant notification to user
space for correct action. Update fb driver and cmd
interface to support the BTA failure scenario.

Change-Id: Ic78379b31a48278282182fdba6ba7b2e6f9c26d5
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>