snap: use const for descriptor

Protocols should be able to use constant value for the descriptor.
Minor whitespace cleanup as well

Signed-off-by: Stephen Hemminger <[e-mail]>
Acked-by: Arnaldo Carvalho de Melo <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/psnap.h

···
 #ifndef _NET_PSNAP_H
 #define _NET_PSNAP_H
 
-extern struct datalink_proto *register_snap_client(unsigned char *desc, int (*rcvfunc)(struct sk_buff *, struct net_device *, struct packet_type *, struct net_device *orig_dev));
+extern struct datalink_proto *
+register_snap_client(const unsigned char *desc,
+		     int (*rcvfunc)(struct sk_buff *, struct net_device *,
+				    struct packet_type *,
+				    struct net_device *orig_dev));
 extern void unregister_snap_client(struct datalink_proto *proto);
 
 #endif

net/802/psnap.c

···
 /*
  *	Find a snap client by matching the 5 bytes.
  */
-static struct datalink_proto *find_snap_client(unsigned char *desc)
+static struct datalink_proto *find_snap_client(const unsigned char *desc)
 {
 	struct datalink_proto *proto = NULL, *p;
 
···
 /*
  *	Register SNAP clients. We don't yet use this for IP.
  */
-struct datalink_proto *register_snap_client(unsigned char *desc,
+struct datalink_proto *register_snap_client(const unsigned char *desc,
 					    int (*rcvfunc)(struct sk_buff *,
 							   struct net_device *,
 							   struct packet_type *,
···
 
 	proto = kmalloc(sizeof(*proto), GFP_ATOMIC);
 	if (proto) {
-		memcpy(proto->type, desc,5);
+		memcpy(proto->type, desc, 5);
 		proto->rcvfunc		= rcvfunc;
 		proto->header_length	= 5 + 3; /* snap + 802.2 */
 		proto->request		= snap_request;