mdss: display: add command mode mdp fifo underflow recovery

At command mode, mdp underflow can not be recovered but cause
mdp to hang up. Add mdp underflow recovery mechanism  when mdp
underflow detected.

Change-Id: I26fc64005ac247372257aa126f2c8c0076925bb9
Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>