net: Allow filtering on debug traces in the net subsystem

Add several levels of DEBUG prints so that you can limit the noise to
the severety of your problem.

DEBUG_LL_STATE = Link local state machine changes
DEBUG_DEV_PKT = Packets or info directed to the device
DEBUG_NET_PKT = Packets on info on the network at large
DEBUG_INT_STATE = Internal network state changes

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/net/ping.c b/net/ping.c
index 2ba9f76..0710b92 100644
--- a/net/ping.c
+++ b/net/ping.c
@@ -45,7 +45,7 @@
 
 	/* XXX always send arp request */
 
-	debug("sending ARP for %pI4\n", &NetPingIP);
+	debug_cond(DEBUG_DEV_PKT, "sending ARP for %pI4\n", &NetPingIP);
 
 	NetArpWaitPacketIP = NetPingIP;
 
@@ -93,7 +93,7 @@
 	case ICMP_ECHO_REQUEST:
 		eth_hdr_size = net_update_ether(et, et->et_src, PROT_IP);
 
-		debug("Got ICMP ECHO REQUEST, return "
+		debug_cond(DEBUG_DEV_PKT, "Got ICMP ECHO REQUEST, return "
 			"%d bytes\n", eth_hdr_size + len);
 
 		ip->ip_sum = 0;