pan/bi: Don't swizzle scalars

Pointless, already replicated.

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10627>

src/panfrost/bifrost/bi_lower_swizzle.c

@@ -74,6 +74,11 @@ bi_lower_swizzle_16(bi_context *ctx, bi_instr *ins, unsigned src)
         if (ins->src[src].swizzle == BI_SWIZZLE_H01)
                 return;
 
+        /* If the instruction is scalar we can ignore the other component */
+        if (ins->dest[0].swizzle == BI_SWIZZLE_H00 &&
+                        ins->src[src].swizzle == BI_SWIZZLE_H00)
+                return;
+
         /* Lower it away */
         bi_builder b = bi_init_builder(ctx, bi_before_instr(ins));
         ins->src[src] = bi_replace_index(ins->src[src],