ath(4) now defaults to 802.11n on GENERIC/i386 and GENERIC/amd64

Hi,

I've flipped on ATH_ENABLE_11N and the interrupt mitigation in i386
and amd64 GENERIC.

I'll flip it on on PPC when someone (chmee?) verifies that 802.11n works on PPC.

It's still delicate. I still don't know if RTS/CTS HT frame protection
is working quite right on all chips. But all the basics are there
(software TX aggregation, RX AMPDU reordering in net80211, BAR
transmission, software queue pause and unpause, frame retransmission.)

Don't be surprised if your 802.11n mobile devices perform poorly as
the power queue handling is very broken and will result in all kinds
of weird traffic stalls if things are too aggressive. I'll look into
fixing that soon.

If you have problems, please read the wiki article:
http://wiki.freebsd.org/dev/ath(4) - specifically the bits where I
tell you to compile with the debugging and diagnostic stuff in your
-HEAD kernel, including the HAL/driver diagnostic APIs and tools.

Enjoy,



Adrian