nl80211: always accept scan request with the duration set

Accept a scan request with the duration set even if the driver
does not support setting the scan dwell. The duration can be used
as a hint to the driver, but the driver may use its internal logic
for setting the scan dwell.
Signed-off-by: Avraham Stern <avraham.stern@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20201129172929.9491a12f9226.Ia9c5b24fcefc5ce5592537507243391633a27e5f@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -8243,12 +8243,6 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
 	}
 
 	if (info->attrs[NL80211_ATTR_MEASUREMENT_DURATION]) {
-		if (!wiphy_ext_feature_isset(wiphy,
-					NL80211_EXT_FEATURE_SET_SCAN_DWELL)) {
-			err = -EOPNOTSUPP;
-			goto out_free;
-		}
-
 		request->duration =
 			nla_get_u16(info->attrs[NL80211_ATTR_MEASUREMENT_DURATION]);
 		request->duration_mandatory =