MFC r333221: rsu(4) does not require legal.realtek.license_ack=1

The rsu firmware license check has been disabled since r292756. Changes
rsu(4) since the license ack is no longer required.

While here, add `device rsufw` hint to the kernel configuration lines and
add/update paths to the installed license file in both rsu(4) and rsufw(4).

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Rename the /usr/share/doc/legal files to driver.LICENSE to work around
bug of installing 'realtek' and 'intel_iwn' as files rather then as
a 'LICENSE' file in their directories.

Also add obsolete entries for the older names and names that existed in head
for a period of time.

Suggested by: jmg
X-MFC-With: r289391
MFC after: 3 weeks
Sponsored by: EMC / Isilon Storage Division

Fix date.

Noticed by: bdrewery

rsu(4) manpage updates: add me, add 802.11n support, update caveats.

* Add that I indeed added 802.11n support.
* Update caveats - we support 1x1, 1x2 and 2x2 operation now, but
there's no transmit aggregation support.

Yes, it supports 802.11n.

Sort SEE ALSO

Add Trendnet TEW-646UBH.

Submitted by: bolshakov_1 at yahoo dot com

use .Mt to mark up email addresses consistently (final part)

PR: 191174
Submitted by: Franco Fichtner <franco at lastsummer.de>

Make this manpage ready for hardware notes generation, add more Xrefs and perform
general cleanup.

In particular, don't claim rsu(4) devices can be configured with hostname(1)...

MFC after: 1 week

add missing sections, de-Xr non-existent page, properly space
punctuation..

Approved by: re (joel)
MFC after: 3 days

mdoc: remove commented out macro, sort SEE ALSO and add missing .El.

Import OpenBSD's rsu(4) WLAN driver.
Support chipsets are the Realtek RTL8188SU, RTL8191SU, and RTL8192SU.

Many thanks to Idwer Vollering for porting/writing the man page and for
testing.

Reviewed by: adrian, hselasky
Obtained from: OpenBSD
Tested by: kevlo, Idwer Vollering <vidwer at gmail.com>