LinuxKPI: netdev features style, annotate, and add %b decoding mask

Start to sort through the netdevice features to match them with
FreeBSD. Annotate them a bit more verbose though the names are
pretty telling already.

While here adjust style(9) as well.

Lastly add the bit definitions for use with printf(9) %b as names
read easier than bitmasks. We will use that in LinuxKPI 802.11.

No functional changes.

Sponsored by: The FreeBSD Foundation

(cherry picked from commit 4b6b9c1368b346f7093153d14e7931403ac3202d)