mac80211: add rtlwifi drivers

Signed-off-by: Viktar Palstsiuk <viktar.palstsiuk@promwad.com>
[jogo@openwrt.org: add missing DRIVER_11N_SUPPORT select, add missing
		   usb dependencies, backport upstream fixes for Kconfig
		   issues]
Signed-off-by: Jonas Gorski <jogo@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt@37687 3c298f89-4303-0410-b956-a3cf2f4a3e73