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

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

Multi-bss (aka vap) support for 802.11 devices.

Note this includes changes to all drivers and moves some device firmware
loading to use firmware(9) and a separate module (e.g. ral). Also there
no longer are separate wlan_scan* modules; this functionality is now
bundled into the wlan module.

Supported by: Hobnob and Marvell
Reviewed by: many
Obtained from: Atheros (some bits)

Add support for Marvell Libertas 88W8335 based PCI network adapters.

Reviewed by: sam, many wireless people
Approved by: thompsa (mentor)