netpacket/sockaddr_ll: Add valid packet types for sll_pkttype

Add valid packet types for the sll_pkttype member of the struct
sockaddr_ll. These definitions are commonly used by third-party
libraries.

include/netpacket/packet.h

@@ -30,6 +30,20 @@
 #include <nuttx/config.h>
 #include <stdint.h>
 
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* Valid packet types for sll_pkttype */
+
+#define PACKET_HOST       0   /* To us.  */
+#define PACKET_BROADCAST  1   /* To all.  */
+#define PACKET_MULTICAST  2   /* To group.  */
+#define PACKET_OTHERHOST  3   /* To someone else.  */
+#define PACKET_OUTGOING   4   /* Originated by us . */
+#define PACKET_LOOPBACK   5
+#define PACKET_FASTROUTE  6
+
 /****************************************************************************
  * Public Types
  ****************************************************************************/