media: vivid: fix assignment of dev->fbuf_out_flags

Currently the chroma_flags and alpha_flags are being zero'd with a bit-wise
mask and the following statement should be bit-wise or'ing in the new flag
bits but instead is making a direct assignment. Fix this by using the |=
operator rather than an assignment.

Addresses-Coverity: ("Unused value")

Fixes: ef834f7836ec ("[media] vivid: add the video capture and output parts")
Signed-off-by: Colin Ian King <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/test-drivers/vivid/vivid-vid-out.c

···
 		return -EINVAL;
 	}
 	dev->fbuf_out_flags &= ~(chroma_flags | alpha_flags);
-	dev->fbuf_out_flags = a->flags & (chroma_flags | alpha_flags);
+	dev->fbuf_out_flags |= a->flags & (chroma_flags | alpha_flags);
 	return 0;
 }