intel/fs: fix per vertex input clamping

intel/fs: fix per vertex input clamping

Only apply the clamp in multi patch mode (where the input vertices
vary between [1, 32]).

The clamp NIR pass operates on lowered intrinsics so we need to call
it after the inputs have been lowered.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Fixes: e25e17dd0c ("intel/fs: clamp per vertex input accesses to patchControlPoints")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/8912
Reviewed-by: Ivan Briano <ivan.briano@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22701>