[BNX2]: check return of dev_alloc_skb in bnx2_test_loopback

Check return of dev_alloc_skb in bnx2_test_loopback, and handle
appropriately.
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/bnx2.c

@@ -3903,6 +3903,8 @@ bnx2_test_loopback(struct bnx2 *bp)
 
 	pkt_size = 1514;
 	skb = dev_alloc_skb(pkt_size);
+	if (!skb)
+		return -ENOMEM;
 	packet = skb_put(skb, pkt_size);
 	memcpy(packet, bp->mac_addr, 6);
 	memset(packet + 6, 0x0, 8);