turnip: Offset by component when lowering gl_TessLevel*

turnip: Offset by component when lowering gl_TessLevel*

lower_tess_ctrl_block assumes that the gl_TessLevel*
intrinsic_store_outputs have already been collapsed into a single
instruction before the tess lowering step:

store_output ... /* base=0 */ /* wrmask=xyzw */ /* component=0 */
store_output ... /* base=1 */ /* wrmask=xy */ /* component=0 */

While this is true in fd because of st_nir_vectorize_io, we don't do
the same lowering in turnip so each tess level component still has
its own store instruction:

store_output ... /* base=0 */ /* wrmask=x */ /* component=0 */
store_output ... /* base=0 */ /* wrmask=x */ /* component=1 */
store_output ... /* base=0 */ /* wrmask=x */ /* component=2 */
store_output ... /* base=0 */ /* wrmask=x */ /* component=3 */
store_output ... /* base=1 */ /* wrmask=x */ /* component=0 */
store_output ... /* base=1 */ /* wrmask=x */ /* component=1 */

This commit adds a component offset to the tess control lowering. An
alternative is to also perform nir_lower_io_to_vector in turnip, but
ir3 seems to generate the same assembly either way and it's nice to
not have a lowering prereq before tess lowering.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5059>