CameraBuf::acquire : using a scoped lock (#19764)

* Using a scoped lock

* Trigger Build

selfdrive/camerad/cameras/camera_common.cc

@@ -121,14 +121,14 @@ CameraBuf::~CameraBuf() {
 }
 
 bool CameraBuf::acquire() {
+  {
     std::unique_lock<std::mutex> lk(frame_queue_mutex);
-
     bool got_frame = frame_queue_cv.wait_for(lk, std::chrono::milliseconds(1), [this]{ return !frame_queue.empty(); });
     if (!got_frame) return false;
 
     cur_buf_idx = frame_queue.front();
     frame_queue.pop();
-  lk.unlock();
+  }
 
   const FrameMetadata &frame_data = camera_bufs_metadata[cur_buf_idx];
   if (frame_data.frame_id == -1) {