net: ieee802154: stop dump llsec devkeys for monitors

[ Upstream commit 080d1a57a94d93e70f84b7a360baa351388c574f ]

This patch stops dumping llsec devkeys for monitors which we don't support
yet. Otherwise we will access llsec mib which isn't initialized for
monitors.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Link: https://lore.kernel.org/r/20210405003054.256017-10-aahringo@redhat.com


Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>