tv: clear preview callback before release.

Prevents native callbacks after camera is released.

Change-Id: I9ef6dc22a46b7d3fd01591c6fa17e460da03ffb0

jami-android/app/src/main/java/cx/ring/tv/main/HomeActivity.kt

@@ -228,6 +228,7 @@ class HomeActivity : FragmentActivity() {
         paused = true
         mCameraPreview?.let { preview ->
             mCamera?.let { camera ->
+                camera.setPreviewCallback(null)
                 camera.release();
                 mCamera = null
             }
@@ -243,6 +244,7 @@ class HomeActivity : FragmentActivity() {
         mDisposableBag.dispose()
         mCameraManager?.unregisterAvailabilityCallback(mCameraAvailabilityCallback)
         mCamera?.let { camera ->
+            camera.setPreviewCallback(null)
             camera.release();
             mCamera = null
         }