Add SIOCGI2C ioctl support to the driver. Would work only on ConnectX-3
with fresh firmware. The low level code is based on code provided by
Mellanox.

Thanks to Mellanox and their distributor Must (http://mustcompany.ru)
for providing hardware.

In collaboration with: Andre Melkoumian <andre mellanox.com>
Reviewed by: hselasky
Sponsored by: Netflix
Sponsored by: Nginx, Inc.