rt2800usb: do not wipe out USB_DMA_CFG settings

We should not reset USB_DMA_CFG on rt2800usb_init_registers() as this
function is called indirectly from rt2800_enable_radio(). If we
do so, we wipe out USB_DMA_CFG settings from rt2800usb_enable_radio().
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ralink/rt2x00/rt2800usb.c

@@ -341,8 +341,6 @@ static int rt2800usb_init_registers(struct rt2x00_dev *rt2x00dev)
 	rt2x00_set_field32(&reg, MAC_SYS_CTRL_RESET_BBP, 1);
 	rt2x00usb_register_write(rt2x00dev, MAC_SYS_CTRL, reg);
 
-	rt2x00usb_register_write(rt2x00dev, USB_DMA_CFG, 0x00000000);
-
 	rt2x00usb_vendor_request_sw(rt2x00dev, USB_DEVICE_MODE, 0,
 				    USB_MODE_RESET, REGISTER_TIMEOUT);
 
@@ -353,12 +351,11 @@ static int rt2800usb_init_registers(struct rt2x00_dev *rt2x00dev)
 
 static int rt2800usb_enable_radio(struct rt2x00_dev *rt2x00dev)
 {
-	u32 reg;
+	u32 reg = 0;
 
 	if (unlikely(rt2800_wait_wpdma_ready(rt2x00dev)))
 		return -EIO;
 
-	rt2x00usb_register_read(rt2x00dev, USB_DMA_CFG, &reg);
 	rt2x00_set_field32(&reg, USB_DMA_CFG_PHY_CLEAR, 0);
 	rt2x00_set_field32(&reg, USB_DMA_CFG_RX_BULK_AGG_EN, 0);
 	rt2x00_set_field32(&reg, USB_DMA_CFG_RX_BULK_AGG_TIMEOUT, 128);