Such glitch happened after the autonegotation FSM was in pseudo
AN_ENABLED state caused by synced=LOW (in this state, link_ok is
HIGH). When synced goes HIGH, the FSM enters "proper" AN_ENABLED
state, it drives link_ok LOW.s All in all, this glitch is avoided
then we use delayed synced_d1 to produce the final link_ok_o.
I did it here to avoid any changes to autonegotiation state machine.