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

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

"Upgrade" the AR9285 code to support PCI/ART EEPROM on flash.

I've just verified that this boots on an Atheros AP91. I haven't verified
it with traffic though, so YMMV.

Remove the EEPROM minor >= 19 check for txgaintype; that's only needed for
Merlin / v14 eeprom formats.

Approved by: re (kib, blanket)

Prepare for embedded use of the AR9285/AR9287.

Calibration/PCI data that's written to flash (rather than EEPROM attached
to the NIC) is typically already in host-endian. The existing checks
end up swapping 16 bit words incorrectly - the correct solution would be
to read the magic value and determine the EEPROM endianness from that.
(This is what Linux does.)

This doesn't completely enable embedded use of the AR9285/AR9287 -
notably, the EEPROM read methods need to be made generic and available
to all EEPROM drivers. I'll worry about that later.

Approved by: re (kib)

Fix the eeprom set API method to return HAL_STATUS.

The code assumed it could return HAL_OK, HAL_EINVAL and other
HAL_STATUS types; so it shouldn't be declared as returning HAL_BOOL.

This commit was brought to you by the Clang compiler.

Submitted by: Matthew Fleming <mdf356@gmail.com>

Fix the Atheros V4K EEPROM definitions to match those in ath9k.

It turns out that the V4K eeprom definitions (used by the AR9285 and
its derivatives) is wrong. These values are at least causing issues
on my AR2427.

With this fix (and initvals in a subsequent commit), the AR2427 behaves
a lot better.

Note - there's still significant drift between the ath9k v4k eeprom
init code (again, used by AR9285 and derivatives) and what's in this
tree. That needs to be investigated and resolved.

Modify the v14/v4k eeprom diag interface to return the whole eeprom.

The v1 and v3 interfaces returned the whole EEPROM but the v14/v4k
interfaces just returned the base header. There's extra information
outside of that which would also be nice to get access to.

Bring in a couple of fixes from the Linux ath9k related to chip hangs.
While there, try to make the register write pattern look like what's
done by ath9k.

MFC after: 3 days

Atheros EEPROM version 4K. This version is mostly based on version 1.4.
This is needed by the upcoming AR9285 support.
Information on the layout gathered from Linux ath9k.

Not yet connected to the build.

Tested by: Eugeny Dzhurinsky