Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

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

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

Bring over the initial 802.11n bluetooth coexistence support code.

The Linux ath9k btcoex code is based off of this code.

Note this doesn't actually implement functional btcoex; there's some
driver glue and a whole lot of verification that is required.

On the other hand, I do have the AR9285+BT and AR9287+BT NICs which
this code supports..

Obtained from: Qualcomm Atheros, Linux ath9k

Since the only thing with a mux is the AR5416 and later, and we're now
doing split software/hardware LED configuration, we can now simply
treat "softled" as an "output" mux type.

This works fine on this DWA-552. Previous generation (pre-11n NICs) don't
have a GPIO mux - only input/output configuration - so they ignore this
field.

Flesh out configurable hardware based LED blinking.

The hardware (MAC) LED blinking involves a few things:

* Selecting which GPIO pins map to the MAC "power" and "network" lines;
* Configuring the MAC LED state (associated, scanning, idle);
* Configuring the MAC LED blinking type and speed.

The AR5416 HAL configures the normal blinking setup - ie, blink rate based
on TX/RX throughput. The default AR5212 HAL doesn't program in any
specific blinking type, but the default of 0 is the same.

This code introduces a few things:

* The hardware led override is configured via sysctl 'hardled';
* The MAC network and power LED GPIO lines can be set, or left at -1
if needed. This is intended to allow only one of the hardware MUX
entries to be configured (eg for PCIe cards which only have one LED
exposed.)

TODO:

* For AR2417, the software LED blinking involves software blinking the
Network LED. For the AR5416 and later, this can just be configured
as a GPIO output line. I'll chase that up with a subsequent commit.

* Add another software LED blink for "Link", separate from "activity",
which blinks based on the association state. This would make my
D-Link DWA-552 have consistent and useful LED behaviour (as they're
marked "Link" and "Activity."

* Don't expose the hardware LED override unless it's an AR5416 or later,
as the previous generation hardware doesn't have this multiplexing
setup.

Refactor out the software LED config code into a common function, called
ath_led_config().

The eventual aim is to have both software and hardware based LED
configuration done here.

First pass of LED related code changes.

Migrate the LED code out of if_ath.c and into if_ath_led.c.
These routines are _all_ software based LED blinking.