Revert "Warn the user if lowres > max_lowres, set lowres to max_lowres and continue"

Changing the lowres value is risky because the user application may have a
local copy and not read back into it, or not undo some lowres dependant things.
A patch implementing this in ffplay is already on ffmpeg-dev, so this feature
should be back soon.

This reverts commit 125ea3ee06.

libavcodec/utils.c

@@ -635,9 +635,10 @@ int attribute_align_arg avcodec_open2(AVCodecContext *avctx, AVCodec *codec, AVD
     }
 
     if (avctx->codec->max_lowres < avctx->lowres || avctx->lowres < 0) {
-        av_log(avctx, AV_LOG_WARNING, "The maximum value for lowres supported by the decoder is %d\n",
+        av_log(avctx, AV_LOG_ERROR, "The maximum value for lowres supported by the decoder is %d\n",
                avctx->codec->max_lowres);
-        avctx->lowres = avctx->codec->max_lowres;
+        ret = AVERROR(EINVAL);
+        goto free_and_end;
     }
     if (avctx->codec->encode) {
         int i;