doc/examples/hw_decode: Remove setting deprecated refcounted_frames

When use new decode APIs(avcodec_send_packet/avcodec_receive_frame),
don't need to setting the deprecated field refcounted_frames.
Reviewed-by: wm4 <nfxjfg@googlemail.com>
Signed-off-by: Jun Zhao <mypopydev@gmail.com>

doc/examples/hw_decode.c

@@ -211,7 +211,6 @@ int main(int argc, char *argv[])
         return -1;
 
     decoder_ctx->get_format  = get_hw_format;
-    av_opt_set_int(decoder_ctx, "refcounted_frames", 1, 0);
 
     if (hw_decoder_init(decoder_ctx, type) < 0)
         return -1;