Add support for FTM initiator, i.e. peer measurements with FTM
if the firmware supports FTM.

Additionally, add two defines we depend on in
include/linux/ieee80211.h.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Avraham Stern <avraham.stern@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>