Implement ndo_change_carrier

[bluecmd]

Since we are doing userspace Fibre Channel we want to keep the DMA and the netdevs hot even when the link is down.
Right now doing ip link set up activates the lasers which will cause the initial FC packets to start to flow. This means that between the up and the pcap attachment we will likely lose packets.

Thus we need a way to be able to reset the interface from userspace without taking it down/up. The IFLA_CARRIER is not meant for this, but we can re-use it as a way to force control of the TX laser which will cause a FC state reset.