mdss: Start wait for hist ready state past first kickoff

When the first histogram kickoff is done past reset, it might
be too late into the waiting period of completion. This
would cause a timeout even though data for the frame is made
available and interrupt is generated after timeout. This
causes a histogram read call to return with an error and
delay reading the data.

Edit to make the wait for ready to start after the first
kickoff. Add additional completion to denote first kickoff
and start wait after first kickoff wait has completed.

Change-Id: Ic9156b4d8852520715324707290287eb09df6195
Signed-off-by: Krishna Chaitanya Parimi <cparimi@codeaurora.org>