Add support for the rt2860/rt3090 chipsets from Ralink.

Includes various patches from a lot of people who helped
getting this driver into the current shape.
Signed-off-by: NAlban Browaeys <prahal@yahoo.com>
Signed-off-by: NBenoit PAPILLAULT <benoit.papillault@free.fr>
Signed-off-by: NFelix Fietkau <nbd@openwrt.org>
Signed-off-by: NLuis Correia <luis.f.correia@gmail.com>
Signed-off-by: NMattias Nissler <mattias.nissler@gmx.de>
Signed-off-by: NMark Asselstine <asselsm@gmail.com>
Signed-off-by: NXose Vazquez Perez <xose.vazquez@gmail.com>
Signed-off-by: NIvo van Doorn <IvDoorn@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>