macsec: use after free when deleting the underlying device

macsec_notify() loops over the list of macsec devices configured on the
underlying device when this device is being removed.  This list is part
of the rx_handler data.

However, macsec_dellink unregisters the rx_handler and frees the
rx_handler data when the last macsec device is removed from the
underlying device.

Add macsec_common_dellink() to delete macsec devices without
unregistering the rx_handler and freeing the associated data.

Fixes: 960d5848

 ("macsec: fix memory leaks around rx_handler (un)registration")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>