v4l2_m2m: Mark V4L2 M2M decoders as unsuitable for probing

libavcodec/v4l2_m2m_dec.c

@@ -221,7 +221,8 @@ AVCodec ff_ ## NAME ## _v4l2m2m_decoder = { \
     .receive_frame  = v4l2_receive_frame,\
     .close          = ff_v4l2_m2m_codec_end,\
     .bsfs           = bsf_name, \
-    .capabilities   = AV_CODEC_CAP_HARDWARE | AV_CODEC_CAP_DELAY, \
+    .capabilities   = AV_CODEC_CAP_HARDWARE | AV_CODEC_CAP_DELAY | \
+                      AV_CODEC_CAP_AVOID_PROBING, \
     .wrapper_name   = "v4l2m2m", \
 };