net: ethernet: adi: adin1110: Fix notifiers

ADIN1110 was registering netdev_notifiers on each device probe.
This leads to warnings/probe failures because of double registration
of the same notifier when to adin1110/2111 devices are connected to
the same system.

Move the registration of netdev_notifiers in module init call,
in this way multiple driver instances can use the same notifiers.

Fixes: bc93e19d

 ("net: ethernet: adi: Add ADIN1110 support")
Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>
Link: https://lore.kernel.org/r/20221027095655.89890-2-alexandru.tachici@analog.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>