Merge branch 'review/lanes-v3' into next

Danielle Ratson:

Currently, there is no way of knowing how many lanes will be use to
achieve a wanted speed.
For example, 100G speed can be achieved using: 2X50 or 4X25.

In order to solve that, extend ethtool uAPI with lanes as a new link
mode setting so the command below, for example, will be supported:
$ ethtool -s swp5 lanes N

Patch #1: Update headers with the new parameter.
Patch #2: Support lanes in netlink.
Patch #3: Expose the number of lanes in use.
Patch #4: Add auto-completion for lanes.
Patch #5: Add lanes to man page.

v3:
	* Add a separated patch, patch #1, for uapi headers and squash
	  the rest of it to patch #2.
	* drop unused member lanes in struct link_mode_info