i965: Re-emit l3 state before BLORP executes

i965: Re-emit l3 state before BLORP executes

If BLORP is the first thing to execute, we may not have set the L3$
config yet.  That's not normally a problem but we're about to add code
to BLORP which will look at brw_context::l3::config and we'd like that
to be initialized.  It's also just good practice.

Cc: "20.0" mesa-stable@lists.freedesktop.org
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3454>