agxv: sysval lowering
This adds the initial infrastructure for lowering sysvals in agxv: starting with nir_intrinsic_load_num_workgroups.
This has been designed to allow more intrinsics such as nir_intrinsic_load_base_instance to be easily added in the future.
Passes dEQP-VK.compute.builtin_var.num_work_groups
Signed-off-by: i509VCB git@i509.me