[WIRELESS] cfg80211: New wireless config infrastructure.

This patch creates the core cfg80211 code along with some sysfs bits.
This is a stripped down version to allow mac80211 to function, but
doesn't include any configuration yet except for creating and removing
virtual interfaces.

This patch includes the nl80211 header file but it only contains the
interface types which the cfg80211 interface for creating virtual
interfaces relies on.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>