msm_fb: display: add wait for overlay0 done

Dcs command mode BLT involves both overlay0 done interrupt
and dmap done interrupt. A transaction is start at kickoff and
end with done interrupt.  At some corner cases both overlay0 and
dmap transaction need to be completed before kickoff of new transaction.

Change-Id: I5a3cc6e8255acf2c61fc627d35f990182d226f63
Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>