b43legacy: rewrite and fix rfkill initialization

The rfkill subsystem doesn't like code like that
rfkill_allocate();
rfkill_register();
rfkill_unregister();
rfkill_register(); /* <- This will crash */

This sequence happens with
modprobe b43
ifconfig wlanX up
ifconfig wlanX down
ifconfig wlanX up

Fix this by always re-allocating the rfkill stuff before register.

The patch to b43 by Michael Buesch <mb@bu3sch.de> has been ported to
b43legacy.

Signed-off-by: Stefano Brivio <stefano.brivio@polimi.it>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/b43legacy/rfkill.c b/drivers/net/wireless/b43legacy/rfkill.c
index a366129..b9d38a4 100644
--- a/drivers/net/wireless/b43legacy/rfkill.c
+++ b/drivers/net/wireless/b43legacy/rfkill.c
@@ -48,18 +48,21 @@
 	struct b43legacy_wldev *dev = poll_dev->private;
 	struct b43legacy_wl *wl = dev->wl;
 	bool enabled;
+	bool report_change = 0;
 
 	mutex_lock(&wl->mutex);
 	B43legacy_WARN_ON(b43legacy_status(dev) < B43legacy_STAT_INITIALIZED);
 	enabled = b43legacy_is_hw_radio_enabled(dev);
 	if (unlikely(enabled != dev->radio_hw_enable)) {
 		dev->radio_hw_enable = enabled;
+		report_change = 1;
 		b43legacyinfo(wl, "Radio hardware status changed to %s\n",
 			enabled ? "ENABLED" : "DISABLED");
-		mutex_unlock(&wl->mutex);
+	}
+	mutex_unlock(&wl->mutex);
+
+	if (unlikely(report_change))
 		input_report_key(poll_dev->input, KEY_WLAN, enabled);
-	} else
-		mutex_unlock(&wl->mutex);
 }
 
 /* Called when the RFKILL toggled in software.
@@ -70,10 +73,11 @@
 	struct b43legacy_wl *wl = dev->wl;
 	int err = 0;
 
-	mutex_lock(&wl->mutex);
-	if (b43legacy_status(dev) < B43legacy_STAT_INITIALIZED)
-		goto out_unlock;
+	if (!wl->rfkill.registered)
+		return 0;
 
+	mutex_lock(&wl->mutex);
+	B43legacy_WARN_ON(b43legacy_status(dev) < B43legacy_STAT_INITIALIZED);
 	switch (state) {
 	case RFKILL_STATE_ON:
 		if (!dev->radio_hw_enable) {