msm: mdss: Switch order of histogram completions when disabling hist

There are two completion structures associated with the histogram. When
hist is being disabled, we complete_all() these structures to unblock the
waiting threads, however the completes were not done in the same order as
the waits.

Change-Id: I0dc39d56db9b4f141b619ae41f2c896d2e84c882
Signed-off-by: Benet Clark <benetc@codeaurora.org>