mac802154: fix NOHZ local_softirq_pending 08 warning

When using nanosleep() in an userspace application we get a
ratelimit warning

NOHZ: local_softirq_pending 08

for 10 times.

This patch replaces netif_rx() with netif_rx_ni() which has
to be used from process/softirq context.
The process/softirq context will be called from fakelb driver.

See linux-kernel commit 481a8199 for similar fix.
Signed-off-by: NAlexander Aring <alex.aring@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/mac802154/wpan.c

@@ -389,7 +389,7 @@ void mac802154_wpan_setup(struct net_device *dev)
 
 static int mac802154_process_data(struct net_device *dev, struct sk_buff *skb)
 {
-	return netif_rx(skb);
+	return netif_rx_ni(skb);
 }
 
 static int