headers, net: Use __kernel_sa_family_t in more definitions shared with userland

Complete the work started with commit
6602a4baf4 ('net: Make userland include
of netlink.h more sane').

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/un.h

@@ -1,10 +1,12 @@
 #ifndef _LINUX_UN_H
 #define _LINUX_UN_H
 
+#include <linux/socket.h>
+
 #define UNIX_PATH_MAX	108
 
 struct sockaddr_un {
-	sa_family_t sun_family;	/* AF_UNIX */
+	__kernel_sa_family_t sun_family; /* AF_UNIX */
 	char sun_path[UNIX_PATH_MAX];	/* pathname */
 };