Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Add the 11n chipset RF frontends to the linker set, even though they're not
attached this way.

The AR5212 based NICs have a variety of RF frontends, so there's a linker set
which the AR5212 attach routine calls. The same framework is used for the
AR5416 and later but as there's a fixed RF frontend for each 11n NIC, it
is just directly attached.

However in the case of compiling a cut down HAL (eg _just_ AR9130 WMAC support),
the linker set ends up being empty and this causes the compile to fail.

So this is just a workaround for that - it means those users who wish an 11n
only HAL can compile the 11n chipsets and RF frontend they need, and just
"ath_ar5212" for the AR5212/AR5416 common code, and it'll just work.

Sponsored by: Hobnob, Inc.

Fix the nfarray offsets for the ar2133/ar5133 radio - (AR5416, AR9160, etc.)

The offsets didn't match the assumption that nfarray[] is ordered by the
chainmask bits and programmed via the register order in ar5416_cca_regs[].
This repairs that damage and ensures that chain 1 is programmed correctly.
(And extension channels will now be programmed correctly also.)

This fixes some of the stuck beacons I've been seeing on my AR9160/AR5416
setups - because Chain 1 would be programmed -80 or -85 dBm, which is
higher than the actual noise floor and thus convincing the radio that
indeed it can't ever transmit.

Push the non-AR5416 related stuff into chipset specific directories.

sys/dev/ath/ath_hal/ar5416/ is getting very crowded and further
commits will make it even more crowded. Now is a good time to
shuffle these files out before any more extensive work is done
on them.

Create an ar9003 directory whilst I'm here; ar9003 specific
chipset code will eventually live there.

Bring back AR9285 support. This fixes most of the issues and should be
pretty usable.

MFC after: 1 month