[NETLINK]: Remove references to process ID

People treating the *_pid fields in netlink as a process ID has caused
endless confusion over the years.  The fact that our own netlink.h
does this only adds to the confusion.

So here is a patch to change the comments to refer to it as the port
ID which hopefully will make it clear what the purpose of the fields
really is.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netlink.h

@@ -31,7 +31,7 @@ struct sockaddr_nl
 {
 	sa_family_t	nl_family;	/* AF_NETLINK	*/
 	unsigned short	nl_pad;		/* zero		*/
-	__u32		nl_pid;		/* process pid	*/
+	__u32		nl_pid;		/* port ID	*/
        	__u32		nl_groups;	/* multicast groups mask */
 };
 
@@ -41,7 +41,7 @@ struct nlmsghdr
 	__u16		nlmsg_type;	/* Message content */
 	__u16		nlmsg_flags;	/* Additional flags */
 	__u32		nlmsg_seq;	/* Sequence number */
-	__u32		nlmsg_pid;	/* Sending process PID */
+	__u32		nlmsg_pid;	/* Sending process port ID */
 };
 
 /* Flags values */