macsec: let the administrator set UP state even if lowerdev is down

mainline inclusion
from mainline-4.20
commit 07bddef9
category: bugfix
bugzilla: 6026
CVE: NA

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

Currently, the kernel doesn't let the administrator set a macsec device
up unless its lower device is currently up. This is inconsistent, as a
macsec device that is up won't automatically go down when its lower
device goes down.

Now that linkstate propagation works, there's really no reason for this
limitation, so let's remove it.

Fixes: c09440f7 ("macsec: introduce IEEE 802.1AE driver")
Reported-by: Radu Rendec <radu.rendec@gmail.com>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>