avdevice/lavfi: Simplify non-AV stream check

Fixes a clang warning
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavdevice/lavfi.c

@@ -184,14 +184,6 @@ av_cold static int lavfi_read_header(AVFormatContext *avctx)
             FAIL(AVERROR(EINVAL));
         }
 
-        /* is an audio or video output? */
-        type = inout->filter_ctx->output_pads[inout->pad_idx].type;
-        if (type != AVMEDIA_TYPE_VIDEO && type != AVMEDIA_TYPE_AUDIO) {
-            av_log(avctx,  AV_LOG_ERROR,
-                   "Output '%s' is not a video or audio output, not yet supported\n", inout->name);
-            FAIL(AVERROR(EINVAL));
-        }
-
         if (lavfi->stream_sink_map[stream_idx] != -1) {
             av_log(avctx,  AV_LOG_ERROR,
                    "An output with stream index %d was already specified\n",
@@ -252,6 +244,10 @@ av_cold static int lavfi_read_header(AVFormatContext *avctx)
                                  AV_OPT_SEARCH_CHILDREN);
             if (ret < 0)
                 goto end;
+        } else {
+            av_log(avctx,  AV_LOG_ERROR,
+                   "Output '%s' is not a video or audio output, not yet supported\n", inout->name);
+            FAIL(AVERROR(EINVAL));
         }
 
         lavfi->sinks[i] = sink;