mac80211: convert HW flags to unsigned long bitmap

As we're running out of hardware capability flags pretty quickly,
convert them to use the regular test_bit() style unsigned long
bitmaps.

This introduces a number of helper functions/macros to set and to
test the bits, along with new debugfs code.

The occurrences of an explicit __clear_bit() are intentional, the
drivers were never supposed to change their supported bits on the
fly. We should investigate changing this to be a per-frame flag.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/ath/ar5523/ar5523.c

@@ -1682,9 +1682,9 @@ static int ar5523_probe(struct usb_interface *intf,
 			(id->driver_info & AR5523_FLAG_ABG) ? '5' : '2');
 
 	ar->vif = NULL;
-	hw->flags = IEEE80211_HW_RX_INCLUDES_FCS |
-		    IEEE80211_HW_SIGNAL_DBM |
-		    IEEE80211_HW_HAS_RATE_CONTROL;
+	ieee80211_hw_set(hw, HAS_RATE_CONTROL);
+	ieee80211_hw_set(hw, RX_INCLUDES_FCS);
+	ieee80211_hw_set(hw, SIGNAL_DBM);
 	hw->extra_tx_headroom = sizeof(struct ar5523_tx_desc) +
 				sizeof(struct ar5523_chunk);
 	hw->wiphy->interface_modes = BIT(NL80211_IFTYPE_STATION);