ieee80211: Add a missing extended capability flag definition

Add the "OBSS Narrow Bandwidth RU In OFDMA Tolerance Support" flag
definition to the definitions of the flags covered by the Extended
Capability IE.

Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>