MFC r343889, r344519, r344682, r344719

r343889:
cxgbev(4): Initialize debug_flags from the environment like in the PF driver.

r344519:
cxgbe(4): Use correct port_info in the call to is_bt().

This fixes a panic during configuration if the tx channel of a port
isn't the same as its port id.

Reported by: Fabrice Bruel
Sponsored by: Chelsio Communications

r344682:
cxgbe(4): Don't forget to report link state to the kernel if the link is
already up at attach.

Reported by: Fabrice Bruel @ Orange Business Service
Sponsored by: Chelsio Communications

r344719:
cxgbev(4): Enable 32b port capabilities in the VF driver.

Sponsored by: Chelsio Communications