par_master: Add shutdown function in par_master struct

With this, register_par_master can take care of register_shutdown
as well, and every par master only needs to call
register_par_master instead of calling both register_par_master
and register_shutdown.

Next patches in the chain convert par masters to use new API.

Tested: builds and ninja test

Change-Id: I0fee15d548cdd16678e551eeb351e659812ddf76
Signed-off-by: Anastasia Klimchuk <aklm@chromium.org>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/57154
Original-Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/72232
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
2 files changed