cxgbe(4): Various link/media related improvements.

• Deal with changes to port_type, and not just port_mod when a transceiver is changed. This fixes hot swapping of transceivers of different types (QSFP+ or QSA or QSFP28 in a QSFP28 port, SFP+ or SFP28 in a SFP28 port, etc.).

• Always refresh media information for ifconfig if the port is down. The firmware does not generate tranceiver-change interrupts unless at least one VI is enabled on the physical port. Before this change ifconfig diplayed potentially stale information for ports that were administratively down.

• Always recalculate and reapply L1 config on a transceiver change.

• Display PAUSE settings in ifconfig. The driver sysctls for this continue to work as well.

MFC after: 2 weeks
Sponsored by: Chelsio Communications