wandboard: add rfkill driver

Signed-off-by: Vladimir Ermakov <vooon341@gmail.com>
config: CONFIG_BT_HCIUART=m for wandboard

Wandboard BT module connected thru UART (ttymxc2).
Don't forget blacklist btsdio.

Requires firmware and uploader (in wandboard.org BSP).

Signed-off-by: Vladimir Ermakov <vooon341@gmail.com>
Merge pull request #9 from vooon/v3.11.x-wand

V3.11.x wandboard: add rfkill, enable BT