cfg80211: allow userspace to control supported rates in scan

Some P2P scans are not allowed to advertise
11b rates, but that is a rather special case
so instead of having that, allow userspace
to request the rate sets (per band) that are
advertised in scan probe request frames.

Since it's needed in two places now, factor
out some common code parsing a rate array.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/net/cfg80211.h

@@ -777,6 +777,7 @@ struct cfg80211_ssid {
  * @n_channels: total number of channels to scan
  * @ie: optional information element(s) to add into Probe Request or %NULL
  * @ie_len: length of ie in octets
+ * @rates: bitmap of rates to advertise for each band
  * @wiphy: the wiphy this was for
  * @dev: the interface
  * @aborted: (internal) scan request was notified as aborted
@@ -788,6 +789,8 @@ struct cfg80211_scan_request {
 	const u8 *ie;
 	size_t ie_len;
 
+	u32 rates[IEEE80211_NUM_BANDS];
+
 	/* internal */
 	struct wiphy *wiphy;
 	struct net_device *dev;