frontends/vdpau: Set H264 chroma_format_idc

We don't get the actual value from VDPAU, so hardcode to 4:2:0.

Cc: mesa-stable
Reviewed-by: Ruijing Dong <ruijing.dong@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33396>

src/gallium/frontends/vdpau/decode.c

@@ -41,6 +41,7 @@
 #define AV1_PRIMARY_REF_NONE    AV1_REFS_PER_FRAME
 #define AV1_SUPERRES_DENOM_MIN  9
 #define AV1_SUPERRES_NUM        8
+#define H264_CHROMA_FORMAT_IDC_420 1
 
 /**
  * Create a VdpDecoder.
@@ -362,6 +363,7 @@ vlVdpDecoderRenderH264(struct pipe_h264_picture_desc *picture,
 
    VDPAU_MSG(VDPAU_TRACE, "[VDPAU] Decoding H264\n");
 
+   picture->pps->sps->chroma_format_idc = H264_CHROMA_FORMAT_IDC_420;
    picture->pps->sps->mb_adaptive_frame_field_flag = picture_info->mb_adaptive_frame_field_flag;
    picture->pps->sps->frame_mbs_only_flag = picture_info->frame_mbs_only_flag;
    picture->pps->sps->log2_max_frame_num_minus4 = picture_info->log2_max_frame_num_minus4;