avcodec/tiff: Fix leak on error

Fixes Coverity issue #1516957.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/tiff.c

@@ -2267,8 +2267,10 @@ again:
             group_size = s->width * channels;
 
             tmpbuf = av_malloc(ssize);
-            if (!tmpbuf)
+            if (!tmpbuf) {
+                av_free(five_planes);
                 return AVERROR(ENOMEM);
+            }
 
             if (s->avctx->pix_fmt == AV_PIX_FMT_RGBF32LE ||
                 s->avctx->pix_fmt == AV_PIX_FMT_RGBAF32LE) {