man: macsec: fix macsec related typos

- ip-macsec.8: fix wrong 'device' keyword in 'ip link add device eth0';
add missing description of 'validate' keyword; remove spurious bracket
near 'encrypt' keyword; add missing reference to configuration of 'port'
and 'sci'
- ip-link.8 fix wrong 'es' and 'encoding' keywords in MACsec section

Signed-off-by: Davide Caratti <dcaratti@redhat.com>
2 files changed