nir/spirv: Restrict the number of channels in texture coordinates

Some SPIR-V texturing instructions pack more than the texture coordinate
into the coordinate source.  We need to mask off the unused channels.

Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

src/compiler/spirv/spirv_to_nir.c

@@ -1568,7 +1568,8 @@ vtn_handle_texture(struct vtn_builder *b, SpvOp opcode,
          coord_components++;
 
       coord = vtn_ssa_value(b, w[idx++])->def;
-      p->src = nir_src_for_ssa(coord);
+      p->src = nir_src_for_ssa(nir_channels(&b->nb, coord,
+                                            (1 << coord_components) - 1));
       p->src_type = nir_tex_src_coord;
       p++;
       break;