cfg80211: add start / stop NAN commands

This allows user space to start/stop NAN interface.
A NAN interface is like P2P device in a few aspects: it
doesn't have a netdev associated to it.
Add the new interface type and prevent operations that
can't be executed on NAN interface like scan.

Define several attributes that may be configured by user space
when starting NAN functionality (master preference and dual
band operation)

Signed-off-by: Andrei Otcheretianski <andrei.otcheretianski@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/mlme.c

@@ -634,6 +634,7 @@ int cfg80211_mlme_mgmt_tx(struct cfg80211_registered_device *rdev,
 			 * fall through, P2P device only supports
 			 * public action frames
 			 */
+		case NL80211_IFTYPE_NAN:
 		default:
 			err = -EOPNOTSUPP;
 			break;