[802.11] Allow connecting to spectrum managed networks

Contrary to the IEEE specification, some access points apparently
set the Spectrum Mgmt bit in the capabilities field even when
broadcasting on a 2.4GHz band that does not require spectrum
management. Allow gPXE to attempt to connect to such networks;
if spectrum management is really required, our advertisement
of capabilities not including it will result in an association
failure.

Reported-by: Peter Meyer <residue@xmail.net>

Signed-off-by: Marty Connor <mdc@etherboot.org>

src/net/80211/net80211.c

 		return -ENOSYS;
 	}
 
-	if ( capab & IEEE80211_CAPAB_SPECTRUM_MGMT ) {
-		DBGC ( dev, "802.11 %p cannot handle spectrum managed "
-		       "network\n", dev );
-		return -ENOSYS;
-	}
-
 	dev->phy_flags &= ~( NET80211_PHY_USE_SHORT_PREAMBLE |
 			     NET80211_PHY_USE_SHORT_SLOT );