macsec: use DEV_STATS_INC()

syzbot/KCSAN reported data-races in macsec whenever dev->stats fields
are updated.

It appears all of these updates can happen from multiple cpus.

Adopt SMP safe DEV_STATS_INC() to update dev->stats fields.

Fixes: c09440f7 ("macsec: introduce IEEE 802.1AE driver")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>