iris: Handle runtime-specified local memory size

The value specified in pipe_compute_state is in addition to the implicit
value computed by NIR.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7047>
3 files changed