Some functions in hw/ppc/spapr_events.c get a pointer to the machine
state using qdev_get_machine(). Convert them to get it from their
caller when possible.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20201209170052.1431440-6-groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>