net: cosmetic: Un-typedef Ethernet_t

Separate the Ethernet header from the 802 header.
Base the size constants on the structs.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/net/cdp.c b/net/cdp.c
index 004aae2..63be570 100644
--- a/net/cdp.c
+++ b/net/cdp.c
@@ -109,7 +109,7 @@
 	uchar *pkt;
 	ushort *s;
 	ushort *cp;
-	Ethernet_t *et;
+	struct ethernet_hdr *et;
 	int len;
 	ushort chksum;
 #if	defined(CONFIG_CDP_DEVICE_ID) || defined(CONFIG_CDP_PORT_ID)   || \
@@ -118,7 +118,7 @@
 #endif
 
 	pkt = NetTxPacket;
-	et = (Ethernet_t *)pkt;
+	et = (struct ethernet_hdr *)pkt;
 
 	/* NOTE: trigger sent not on any VLAN */