on "ifconfig -v". I've seen no measurable timing difference
for doing additional SIOCGI2C call for system with 4k vlans.
* Determine appropriate handler (SFP/QSFP) by reading identification
byte (which is the same for both SFF-8472 and SFF-8436) instead
of checking driver name.
MFC with: r270064
Sponsored by: Yandex LLC
5c02a66b2b