net: cosmetic: Un-typedef ICMP_t

Remove typedef and lower-case name

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/net/net.c b/net/net.c
index 6d34254..4cdd9cd 100644
--- a/net/net.c
+++ b/net/net.c
@@ -825,7 +825,7 @@
 static void receive_icmp(struct ip_udp_hdr *ip, int len,
 			IPaddr_t src_ip, struct ethernet_hdr *et)
 {
-	ICMP_t *icmph = (ICMP_t *)&ip->udp_src;
+	struct icmp_hdr *icmph = (struct icmp_hdr *)&ip->udp_src;
 
 	switch (icmph->type) {
 	case ICMP_REDIRECT: