msm: mdss: mask DSI FIFO overflow errors during BTA operation

For some DSI panels where porch values are less, if BTA operation
does not finish in BLLP period, then fake overflow errors are
expected. So disable DSI FIFO overflow errors before triggering
BTA and enable it back once BTA acknowledgment is received for
video mode panels.

Change-Id: If63ac6435f5786c834fe797478c38a9a2f51076b
Signed-off-by: Sandeep Panda <spanda@codeaurora.org>