MT#55283 add missing socket reset flag

We use `family == NULL` as test for the socket being open in several
places, and expect it to match the familt of the addresses. Set it to
zero to make it consistent.

Change-Id: Ide2b41e84fc27b5f47f579dcf4ab2ec2f6b0a37e
(cherry picked from commit 16de9688d6)

lib/socket.c

@@ -880,6 +880,7 @@ bool reset_socket(socket_t *r) {
 		return false;
 
 	r->fd = -1;
+	r->family = NULL;
 	ZERO(r->local);
 	ZERO(r->remote);