[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: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/bnx2.c b/drivers/net/bnx2.c
index 65aae28..32267d5 100644
--- a/drivers/net/bnx2.c
+++ b/drivers/net/bnx2.c
@@ -3903,6 +3903,8 @@
 
 	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);