Currently we get an inconsistent state:
 - netlink returns the error to userspace
 - the RXSC is installed but not offloaded

Then the device could get confused when we try to add an RXSA, because
the RXSC isn't supposed to exist.

Fixes: 3cf3227a ("net: macsec: hardware offloading infrastructure")
Signed-off-by: NSabrina Dubroca <sd@queasysnail.net>
Reviewed-by: NAntoine Tenart <atenart@kernel.org>
Reviewed-by: NLeon Romanovsky <leonro@nvidia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>