pan/va: Validate FAU before packing

These are pre-conditions required for packing.

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15223>

src/panfrost/bifrost/valhall/va_pack.c

@@ -836,6 +836,8 @@ bi_pack_valhall(bi_context *ctx, struct util_dynarray *emission)
 {
    unsigned orig_size = emission->size;
 
+   va_validate(stderr, ctx);
+
    bi_foreach_block(ctx, block) {
       bi_foreach_instr_in_block(block, I) {
          unsigned flow = va_pack_flow(block, I);