nir: Allow more deref modes in phis

In particular, OpenCL needs to allow shader_temp and function_temp
through because they're 100% real pointers.

Fixes piglit CL calls.cl

Reviewed-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7092>
2 files changed