anv,iris: Fix input vertex max for tcs on gen12

anv,iris: Fix input vertex max for tcs on gen12

gen12 does away with the single patch dispatch mode for tcs, and
increases some limits so that 8_patch mode can always work. Make the
necessary changes so we don't try to fall back to single patch mode.

Fixes KHR-GL46.tessellation_shader.single.max_patch_vertices and others

Fixes: 44754279ace7 ("intel/fs/gen12: Use TCS 8_PATCH mode.")
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4843>