v3d: Add support for CS workgroup/invocation id intrinsics.

We get a payload for the ivec3 workgroup and an int local invocation
index, and we use the core lowering to turn into the global invocation id
and the local invocation id ivec3s.

src/broadcom/compiler/vir.c

@@ -639,6 +639,7 @@ v3d_lower_nir(struct v3d_compile *c)
         }
 
         NIR_PASS_V(c->s, nir_lower_tex, &tex_options);
+        NIR_PASS_V(c->s, nir_lower_system_values);
 }
 
 static void