media: verisilicon: av1: Fix reference video buffer pointer assignment

Always get new destination buffer for reference frame because nothing
garantees the one set previously is still valid or unused.

Fixes this chromium test suite:
https://chromium.googlesource.com/chromium/src/media/+/refs/heads/main/test/data/test-25fps.av1.ivf

Fixes: 727a400 ("media: verisilicon: Add Rockchip AV1 decoder")
Cc: <stable@vger.kernel.org>
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
[hverkuil: fix typo and add link to chromium test suite]

Author: Benjamin Gaignard

drivers/media/platform/verisilicon/rockchip_vpu981_hw_av1_dec.c

@@ -161,8 +161,7 @@ static int rockchip_vpu981_av1_dec_frame_ref(struct hantro_ctx *ctx,
 		av1_dec->frame_refs[i].timestamp = timestamp;
 		av1_dec->frame_refs[i].frame_type = frame->frame_type;
 		av1_dec->frame_refs[i].order_hint = frame->order_hint;
-		if (!av1_dec->frame_refs[i].vb2_ref)
-			av1_dec->frame_refs[i].vb2_ref = hantro_get_dst_buf(ctx);
+		av1_dec->frame_refs[i].vb2_ref = hantro_get_dst_buf(ctx);
 
 		for (j = 0; j < V4L2_AV1_TOTAL_REFS_PER_FRAME; j++)
 			av1_dec->frame_refs[i].order_hints[j] = frame->order_hints[j];