from_lavc_pf_priority: do not advertise HW_VDPAU

This is handled differently and may trigger unexpected decode to HW_VDPAU
if gl display advertises that, eg. `uv -t testcard -c lavc:c=MJPG -d gl`.

This fixes the commit 647d862 (2025-06-25) that unintentionally
enabled that.

The HW accel is hanndled actually separately ahd snouldn't be "enabled"
in this way.

Author: MartinPulec

src/libavcodec/from_lavc_vid_conv.c

@@ -3173,6 +3173,10 @@ av_to_uv_convert(const av_to_uv_convert_t *convert,
 int
 from_lavc_pf_priority(struct pixfmt_desc internal, codec_t ugc)
 {
+        if (codec_is_hw_accelerated(ugc)) {
+                return VDEC_PRIO_NA;
+        }
+
         bool found_a_conversion = false;
         for (unsigned i = 0; i < countof(av_to_uv_conversions); i++) {
                 if (av_to_uv_conversions[i].uv_codec == ugc) {