aco: remove isel_context::allocated

Now that we have Program::temp_rc, we can replace it with the first
temporary id allocated for NIR's ssa defs.

No fossil-db changes on Navi.

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7067>
4 files changed