Do not release recording frames if camera is gone

Change-Id: Ia6038c1a3ca17207e43a955ec47c42cdff1f5a76
related-to-bug: 5129465
diff --git a/media/libstagefright/CameraSource.cpp b/media/libstagefright/CameraSource.cpp
index ea8eaa4..ac3565f 100755
--- a/media/libstagefright/CameraSource.cpp
+++ b/media/libstagefright/CameraSource.cpp
@@ -665,7 +665,7 @@
     LOGV("releaseRecordingFrame");
     if (mCameraRecordingProxy != NULL) {
         mCameraRecordingProxy->releaseRecordingFrame(frame);
-    } else {
+    } else if (mCamera != NULL) {
         int64_t token = IPCThreadState::self()->clearCallingIdentity();
         mCamera->releaseRecordingFrame(frame);
         IPCThreadState::self()->restoreCallingIdentity(token);