sctp: Replace sockaddr with sockaddr_inet in sctp_addr union

As part of the removal of the variably-sized sockaddr for kernel
internals, replace struct sockaddr with sockaddr_inet in the sctp_addr
union.

No binary changes; the union size remains unchanged due to sockaddr_inet
matching the size of sockaddr_in6.

Signed-off-by: Kees Cook <kees@kernel.org>
Link: https://patch.msgid.link/20250722171836.1078436-3-kees@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kees

include/net/sctp/structs.h

@@ -51,9 +51,9 @@
  * We should wean ourselves off this.
  */
 union sctp_addr {
+	struct sockaddr_inet sa;	/* Large enough for both address families */
 	struct sockaddr_in v4;
 	struct sockaddr_in6 v6;
-	struct sockaddr sa;
 };
 
 /* Forward declarations for data structures. */