rt2x00usb: drop rt2x00usb_disable_radio() from rt2800usb_disable_radio()

I have here FRITZ!WLAN USB Stick N v2 / idVendor=057c, idProduct=8501
and every single of this requests ends up with:

|ieee80211 phy0: rt2x00usb_vendor_request: Error - Vendor Request 0x0c  failed for offset 0x0000 with error -32

I was browsing the the vedor code and I haven't seen such request so I
remove it with this patch. If I wasn't look enough or if this error is
expected then please excuse :)
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/rt2x00/rt2800usb.c

@@ -378,7 +378,6 @@ static int rt2800usb_enable_radio(struct rt2x00_dev *rt2x00dev)
 static void rt2800usb_disable_radio(struct rt2x00_dev *rt2x00dev)
 {
 	rt2800_disable_radio(rt2x00dev);
-	rt2x00usb_disable_radio(rt2x00dev);
 }
 
 static int rt2800usb_set_state(struct rt2x00_dev *rt2x00dev,