net: ieee802154: atusb: Replace GFP_ATOMIC with GFP_KERNEL in atusb_probe

atusb_probe() is never called in atomic context.
This function is only set as ".probe" in struct usb_driver.

Despite never getting called from atomic context,
atusb_probe() calls usb_alloc_urb() with GFP_ATOMIC,
which does not sleep for allocation.
GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
which can sleep and improve the possibility of sucessful allocation.

This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Stefan Schmidt <stefan@osg.samsung.com>

drivers/net/ieee802154/atusb.c

@@ -1045,7 +1045,7 @@ static int atusb_probe(struct usb_interface *interface,
 	atusb->tx_dr.bRequest = ATUSB_TX;
 	atusb->tx_dr.wValue = cpu_to_le16(0);
 
-	atusb->tx_urb = usb_alloc_urb(0, GFP_ATOMIC);
+	atusb->tx_urb = usb_alloc_urb(0, GFP_KERNEL);
 	if (!atusb->tx_urb)
 		goto fail;