Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

5416 and later parts mux the gpio outputs; extend the api to include
a signal type that's used to select the appropriate mux

add FreeBSD property

import ath hal

Replace most compile-time support options with linker sets for
chip and RF backend support:
o add OS_DATA_SET and OS_SET_DECLARE os requirements for setting
up linker sets
o add AH_CHIP macro for registering chip support (e.g. 5210)
o add AH_RF macro for registering RF support (e.g. 2413); note
this isn't required for single chip solutions where there's no
ambiguity (e.g. 5416/9160+2133) but for 5212 class parts it's
required because of the multi-chip solutions
o remove all uses of AH_SUPPORT_AR5210, AH_SUPPORT_AR5211, AH_SUPPORT_5212,
and AH_SUPPORT_AR9160; still need AH_SUPPORT_AR5416 to enable the 11n
descriptor formats and 5312 support is presently broken
o remove all uses of AH_SUPPORT_2133, AH_SUPPORT_2413, AH_SUPPORT_5111,
AH_SUPPORT_5112, AH_SUPPORT_2417, AH_SUPPORT_2425, and AH_SUPPORT_5413;
5312-related support still requires fixup

Remaining issues:
o fixup SoC attach
o ath_hal_attach uses a hack to probe w/o access to the vendorid
o fallback handling of parts w/o a macrev needs to be restored

virgin import of ath hal