msm: mdss: hdcp: handle hdcp1 mutex properly

HDCP driver is returning without unlocking hdcp1_ta_cmd_lock
mutex. Unlock it and then return.

Change-Id: Ia2fa1c857516d6fbdd732a6cdbf71236950f88b2
Signed-off-by: Narender Ankam <nankam@codeaurora.org>
Signed-off-by: Ramendra Kumar <ramendra@codeaurora.org>