msm: mdss: protect command mode BW votes by tracking HW/SW states

Track two states where the BW is needed for the command mode panels
and prevent the BW vote to be released during any of those two states:
1. SW Commit State: This state is the time when the SW has requested
a BW vote, and it will be processing it; it starts at the beginning of
Commit and finish once the kickoff is issued.
2. HW MDP State: This state is the time when the HW is busy
doing the actual transaction, so bandwidth must be kept until
HW finishes; it starts at the beginning of the kickoff and finishes
once the ping pong done interrupt is received.

Change-Id: I2e56128be3ab25a1b065692ae76387a3cd383df3
Signed-off-by: Ingrid Gallardo <ingridg@codeaurora.org>