BUILD: connection: avoid a build warning on FreeBSD with SO_USER_COOKIE

It was brough by an unneeded addition of a local variable after a test
in commit f7f53afcf ("BUILD/MEDIUM: tcp: set-mark setting support for
FreeBSD."). No backport needed.
diff --git a/include/haproxy/connection.h b/include/haproxy/connection.h
index 84c6645..17dad4b 100644
--- a/include/haproxy/connection.h
+++ b/include/haproxy/connection.h
@@ -488,8 +488,7 @@
 #if defined(SO_MARK)
 	setsockopt(conn->handle.fd, SOL_SOCKET, SO_MARK, &mark, sizeof(mark));
 #elif defined(SO_USER_COOKIE)
-	uint32_t mval = (uint32_t)mark;
-	setsockopt(conn->handle.fd, SOL_SOCKET, SO_USER_COOKIE, &mval, sizeof(mval));
+	setsockopt(conn->handle.fd, SOL_SOCKET, SO_USER_COOKIE, &mark, sizeof(mark));
 #elif defined(SO_RTABLE)
 	setsockopt(conn->handle.fd, SOL_SOCKET, SO_RTABLE, &mark, sizeof(mark));
 #endif