cfg80211: return -ENOENT when stopping sched_scan while not running

If we try to stop a scheduled scan while it is not running, we should
return -ENOENT instead of simply ignoring the command and returning
success.  This is more consistent with other parts of the code.

Reported-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 5d23503..ce04566 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -137,7 +137,7 @@
 	ASSERT_RDEV_LOCK(rdev);
 
 	if (!rdev->sched_scan_req)
-		return 0;
+		return -ENOENT;
 
 	dev = rdev->sched_scan_req->dev;