[PATCH] selftest: net: fix socklen_t type mismatch in sctp_collision test

[Ankit Khushwaha <ankitkhushwaha.linux@gmail.com>]

Socket APIs like recvfrom(), accept(), and getsockname() expect socklen_t*
arg, but tests were using int variables. This causes -Wpointer-sign 
warnings on platforms where socklen_t is unsigned.

Change the variable type from int to socklen_t to resolve the warning and
ensure type safety across platforms.

warning fixed:

sctp_collision.c:62:70: warning: passing 'int *' to parameter of 
type 'socklen_t *' (aka 'unsigned int *') converts between pointers to 
integer types with different sign [-Wpointer-sign]
   62 |                 ret = recvfrom(sd, buf, sizeof(buf), 
									0, (struct sockaddr *)&daddr, &len);
      |                                                           ^~~~
/usr/include/sys/socket.h:165:27: note: passing argument to 
parameter '__addr_len' here
  165 |                          socklen_t *__restrict __addr_len);
      |                                                ^

Signed-off-by: Ankit Khushwaha <ankitkhushwaha.linux@gmail.com>
---
 tools/testing/selftests/net/netfilter/sctp_collision.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/netfilter/sctp_collision.c b/tools/testing/selftests/net/netfilter/sctp_collision.c
index 21bb1cfd8a85..91df996367e9 100644
--- a/tools/testing/selftests/net/netfilter/sctp_collision.c
+++ b/tools/testing/selftests/net/netfilter/sctp_collision.c
@@ -9,7 +9,8 @@
 int main(int argc, char *argv[])
 {
 	struct sockaddr_in saddr = {}, daddr = {};
-	int sd, ret, len = sizeof(daddr);
+	int sd, ret;
+	socklen_t len = sizeof(daddr);
 	struct timeval tv = {25, 0};
 	char buf[] = "hello";
 
-- 
2.51.0