Bond devices can have any name the user configures, so

Bond devices can have any name the user configures, so
when checking link status for an interface, first
check if this interface is in fact a bond device
(by the precense of a /proc/net/bonding/IFACE file)
and use that file for checking status.

Othervise assume ib* is an infiniband interface which we donnt know how
to check, or otherwise it is an ethernet interface and ethtool should
hopefully work.