drivers:net: Remove unnecessary OOM messages after netdev_alloc_skb

Emitting netdev_alloc_skb and netdev_alloc_skb_ip_align OOM
messages is unnecessary as there is already a dump_stack
after allocation failures.

Other trivial changes around these removals:

Convert a few comparisons of pointer to 0 to !pointer.
Change flow to remove unnecessary label.
Remove now unused variable.
Hoist assignment from if.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/smsc/smsc9420.c b/drivers/net/ethernet/smsc/smsc9420.c
index d457fa2..ffa5c4a 100644
--- a/drivers/net/ethernet/smsc/smsc9420.c
+++ b/drivers/net/ethernet/smsc/smsc9420.c
@@ -848,10 +848,8 @@
 	BUG_ON(pd->rx_buffers[index].skb);
 	BUG_ON(pd->rx_buffers[index].mapping);
 
-	if (unlikely(!skb)) {
-		smsc_warn(RX_ERR, "Failed to allocate new skb!");
+	if (unlikely(!skb))
 		return -ENOMEM;
-	}
 
 	mapping = pci_map_single(pd->pdev, skb_tail_pointer(skb),
 				 PKT_BUF_SZ, PCI_DMA_FROMDEVICE);