- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

Implement basic 802.11n awareness in the PHY and AMRR rate control code.

* Add 802.11n 2ghz and 5ghz tables, including legacy rates and up to
MCS23 rates (3x3.)

* Populate the rate code -> rate index lookup table with MCS _and_
normal rates, but _not_ the basic rate flag. Since the basic rate flag
is the same as the MCS flag, we can only use one.

* Introduce some accessor inlines that do PLCP and rate table lookup/access
and enforce that it doesn't set the basic rate bit. They're not
designed for MCS rates, so it will panic.

* Start converting drivers that use the rate table stuff to use the
accessor inlines and strip the basic flag.

* Teach AMRR about basic 11n - it's still as crap for MCS as it is
being used by iwn, so it's not a step _backwardS_.

* Convert iwn over to accept 11n MCS rates rather than 'translate' legacy
to MCS rates. It doesn't use a lookup table any longer; instead it's a
function which takes the current node (for HT parameters) and the
rate code, and returns the hardware PLCP code to use.

Tested:

* ath - it's a no-op, and it works that way
* iwn - both 11n and non-11n

Mechanically substitute flags from historic mbuf allocator with
malloc(9) flags in sys/dev.

Add support for Ralink RT2800/RT3000 chipsets.

Thanks to ray@, Sevan and Sergey Dyatko for feedback and testing!

Obtained from: OpenBSD
MFC after: 3 weeks