nl80211: support sending TDLS commands/frames

Add support for sending high-level TDLS commands and TDLS frames via
NL80211_CMD_TDLS_OPER and NL80211_CMD_TDLS_MGMT, respectively. Add
appropriate cfg80211 callbacks for lower level drivers.

Add wiphy capability flags for TDLS support and advertise them via
nl80211.

Signed-off-by: Arik Nemtsov <arik@wizery.com>
Cc: Kalyan C Gaddam <chakkal@iit.edu>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

Conflicts:

	include/linux/nl80211.h
	include/net/cfg80211.h
	net/wireless/nl80211.c

Change-Id: I08e4de6e92680aed35b98838aa999d31963b6d50