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

[bwn] add opt_wlan.h and opt_bwn.h so we can enable bwn debugging as appropriate.

Tested:

* BCM4322, STA mode (11a)

Sponsored by: Palm Springs

[bwn] missed commit!

[bwn] implement reset improvements in preparation for PHY-N support

* Ensure we set 20MHz wide channels (hard-coded) for PHY-N.
* Change the core rese tto take a flag saying "gmode" vesus uint32_t
flags. This is important for BCMA support where the "gmode" bit
is different.
* Refactor out the mac-phy clock reset routine (usde by PHY-N).

Tested:

* BCM4321 (PHY-N), BCM4312 (PHY-LP)

TODO:

* Checkpoint test on PHY-G hardware, just to check.

[bwn] migrate bwn_dummy_transmission() back to main, as it'll be used by other PHYs.

The Linux b43 driver uses this in other PHYs besides the g PHY.

[bwn] break out the 'g' phy code into a separate source file.

* Break out the 'g' phy code;
* Break out the debugging bits into a separate source file, since
some debugging prints are done in the phy code;
* Make some more chip methods in if_bwn.c public.

This brings the size of if_bwn.c down to 6,805 lines which is now
approaching managable.