sctp: remove shadowed symbols

Fixes the following sparse warnings:
net/sctp/sm_make_chunk.c:1457:9: warning: symbol 'len' shadows an earlier one
net/sctp/sm_make_chunk.c:1356:23: originally declared here
net/sctp/socket.c:1534:22: warning: symbol 'chunk' shadows an earlier one
net/sctp/socket.c:1387:20: originally declared here
Signed-off-by: Sebastian Siewior <sebastian@breakpoint.cc>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>

net/sctp/sm_make_chunk.c

@@ -1452,7 +1452,6 @@ no_hmac:
 		do_gettimeofday(&tv);
 
 	if (!asoc && tv_lt(bear_cookie->expiration, tv)) {
-		__u16 len;
 		/*
 		 * Section 3.3.10.3 Stale Cookie Error (3)
 		 *

net/sctp/socket.c

@@ -1529,7 +1529,6 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
 			goto out_unlock;
 		}
 		if (sinfo_flags & SCTP_ABORT) {
-			struct sctp_chunk *chunk;
 
 			chunk = sctp_make_abort_user(asoc, msg, msg_len);
 			if (!chunk) {