broadcom/compiler: reset spill/fill counts after lowering thread count.

Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15041>

src/broadcom/compiler/nir_to_vir.c

@@ -4510,6 +4510,8 @@ v3d_nir_to_vir(struct v3d_compile *c)
                 }
 
                 c->spill_count = 0;
+                c->spills = 0;
+                c->fills = 0;
                 c->threads /= 2;
 
                 if (c->threads == 1)