hwc: Do not use the sequence lock in eventcontrol

The eventcontrol is not part of the prepare/set sequence and
hence should not indefinitely wait on the condition to turn
on/off the vsync.

Change-Id: I5f065e68bb3171ee684d2810f4856fc28c287df6
CRs-fixed: 1008557

sdm/libs/hwc/hwc_session.cpp

@@ -432,8 +432,6 @@ void HWCSession::CloseAcquireFds(hwc_display_contents_1_t *content_list) {
 }
 
 int HWCSession::EventControl(hwc_composer_device_1 *device, int disp, int event, int enable) {
-  SEQUENCE_WAIT_SCOPE_LOCK(locker_);
-
   if (!device) {
     return -EINVAL;
   }