net: Inline skb_pull() in eth_type_trans().

In commit 6be8ac2f ("[NET]: uninline skb_pull, de-bloats a lot")
we uninlined skb_pull.

But in some critical paths it makes sense to inline this thing
and it helps performance significantly.

Create an skb_pull_inline() so that we can do this in a way that
serves also as annotation.

Based upon a patch by Eric Dumazet.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
index 0c0d272..61ec032 100644
--- a/net/ethernet/eth.c
+++ b/net/ethernet/eth.c
@@ -162,7 +162,7 @@
 
 	skb->dev = dev;
 	skb_reset_mac_header(skb);
-	skb_pull(skb, ETH_HLEN);
+	skb_pull_inline(skb, ETH_HLEN);
 	eth = eth_hdr(skb);
 
 	if (unlikely(is_multicast_ether_addr(eth->h_dest))) {