- Port ath(4) driver from FreeBSD, which supports various Atheros chip based

- Port ath(4) driver from FreeBSD, which supports various Atheros chip based
  WiFi NIC
- Hook ath(4) into module building
- Add ath(4) and ath_hal(4) manpage
  With-help-from: swildner

Thank Sam Leffler and many other people for their greate work, also thank
Sam Leffler for his kind explaining about some caveats concerning ath_hal(4).

An early version of this driver, which works under DragonFly, was submitted by:
Andrew Atrens <atrens@nortel.com>
and was later modified to work on DragonFly 1.4.x and resubmitted by:
Adrian Michael Nida <nida@musc.edu>

Thank them for their submission.

Obtained-from: FreeBSD (mainly sam@freebsd.org)
Tested-by: many
Approved-by: dillon