msm: mdss: Add an extra write of zero to clear dsi-ack-err bit

In addition to writing 1 to clear dsi-ack-err bit, an extra write
of 0 is also needed to clear error bit completely.

CRs-fixed: 574066
Change-Id: Ib9df9fe5f993605372ced8766874fa00538f505a
Signed-off-by: Shivaraj Shetty <shivaraj@codeaurora.org>