msm: mdss: Move histogram complete_all after hist interrupts disabled

Previously, complete_all was called during histogram disablement before
the histogram interrupts were disabled, which can lead to issues if an
interrupt comes in between complete_all and interrupt disablement. Now,
complete_all is called afterwards, which guarantees no more interrupts
will come.

Change-Id: I1910e59b27ae55dbb2ed89373e2af614ef6a9808
Signed-off-by: Benet Clark <benetc@codeaurora.org>