octeontx2-pf: mcs: fix missing unlock in some error paths

Add the missing unlock in some error paths.

Fixes: c54ffc73

 ("octeontx2-pf: mcs: Introduce MACSEC hardware offloading")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>