lavc/avrndec: remove AV_CODEC_CAP_DR1, as it's broken

In the is_mjpeg case, the user's get_buffer2 callback is not called,
thus completely breaking the API.
Signed-off-by: James Almer <jamrial@gmail.com>

libavcodec/avrndec.c

@@ -168,7 +168,6 @@ AVCodec ff_avrn_decoder = {
     .init           = init,
     .close          = end,
     .decode         = decode_frame,
-    .capabilities   = AV_CODEC_CAP_DR1,
     .max_lowres     = 3,
     .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 };