drm/msm/dsi-staging: fix cmd engine ref count logic

Fix command engine ref count logic which is not decremented
correctly after the command was sent successfully.

Change-Id: I6c6aaedf85bc8eb9f1d05aa657a5f3104f4e5fec
Signed-off-by: Vara Reddy <varar@codeaurora.org>
1 file changed