geom: Push GEOM sysinit ordering to after devctl

GEOM depends on devctl being initialized, as it uses devctl_notify,
which assumes that devctl is initialized already. However, if devctl is
not initialized yet, the devctl UMA zone is NULL, resulting in a panic.
Thus far this has worked seemingly by linker luck that lets devctl sort
before GEOM, but this is not guaranteed. Instead, enforce the ordering
by pushing GEOM to third place, explicitly ordering it after
devctl_init, which is ordered second.

Since g_raid wants to initialize after GEOM, push that to fourth place
as well.

Sponsored by: Juniper Networks, Inc.