net: ethernet: use ip_hdrlen() instead of bit shift

`ip_hdr(skb)->ihl << 2` is the same as `ip_hdrlen(skb)`
Therefore, we should use a well-defined function not a bit shift
to find the header length.

It also compresses two lines to a single line.

Signed-off-by: Moon Yeounsu <[e-mail]>
Reviewed-by: Christophe JAILLET <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/jme.c

···
 	if (skb->protocol != htons(ETH_P_IP))
 		return csum;
 	skb_set_network_header(skb, ETH_HLEN);
-	if ((ip_hdr(skb)->protocol != IPPROTO_UDP) ||
-	    (skb->len < (ETH_HLEN +
-			(ip_hdr(skb)->ihl << 2) +
-			sizeof(struct udphdr)))) {
+
+	if (ip_hdr(skb)->protocol != IPPROTO_UDP ||
+	    skb->len < (ETH_HLEN + ip_hdrlen(skb) + sizeof(struct udphdr))) {
 		skb_reset_network_header(skb);
 		return csum;
 	}
-	skb_set_transport_header(skb,
-			ETH_HLEN + (ip_hdr(skb)->ihl << 2));
+	skb_set_transport_header(skb, ETH_HLEN + ip_hdrlen(skb));
 	csum = udp_hdr(skb)->check;
 	skb_reset_transport_header(skb);
 	skb_reset_network_header(skb);