net: Refactor to use NetSendPacket instead of eth_send directly

Use this entry-point consistently across the net/ code
Use a static inline function to preserve code size

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/include/net.h b/include/net.h
index 128c5ea..3214830 100644
--- a/include/net.h
+++ b/include/net.h
@@ -472,7 +472,10 @@
 extern void	NetSetTimeout(ulong, thand_f *);/* Set timeout handler */
 
 /* Transmit "NetTxPacket" */
-extern void NetSendPacket(uchar *, int);
+static inline void NetSendPacket(uchar *pkt, int len)
+{
+	(void) eth_send(pkt, len);
+}
 
 /*
  * Transmit UDP packet, performing ARP request if needed