staging: dpaa2-switch: move the notifier register to module_init()

Move the notifier blocks register into the module_init() step, instead of
object probe, so that all DPSW devices probed by the dpaa2-switch driver
can use the same notifiers.

This will enable us to have a more straightforward approach in
determining if an event is intended for an object managed by this driver
or not. Previously, the dpaa2_switch_port_dev_check() function was
forced to also check the notifier block beside the net_device_ops
structure to determine if the event is for us or not.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>