net: ieee802154: forbid monitor for del llsec dev

stable inclusion
from stable-5.10.32
commit 4c1775d6ea86e7b72f6bd2028e226c1389d0b2cd
bugzilla: 51796

--------------------------------

[ Upstream commit ad8f9de1 ]

This patch forbids to del llsec dev for monitor interfaces 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/20210405003054.256017-9-aahringo@redhat.com


Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>