avcodec/vble: Don't free buffer known to be NULL

Freeing a buffer allocated in the VBLE decoder's init function
is the only thing the decoder's close function does and this implies
that it is unnecessary to call it in case said allocation fails. Yet
this is what has been done.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavcodec/vble.c

@@ -197,7 +197,6 @@ static av_cold int vble_decode_init(AVCodecContext *avctx)
 
     if (!ctx->val) {
         av_log(avctx, AV_LOG_ERROR, "Could not allocate values buffer.\n");
-        vble_decode_close(avctx);
         return AVERROR(ENOMEM);
     }