net: ignore sock_from_file errors in __scm_install_fd

The code had historically been ignoring these errors, and my recent
refactoring changed that, which broke ssh in some setups.

Fixes: 2618d53 ("net/scm: cleanup scm_detach_fds")
Reported-by: Ido Schimmel <idosch@idosch.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Ido Schimmel <idosch@mellanox.com>
Tested-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/scm.c

@@ -307,7 +307,7 @@ static int __scm_install_fd(struct file *file, int __user *ufd, int o_flags)
 		sock_update_classid(&sock->sk->sk_cgrp_data);
 	}
 	fd_install(new_fd, get_file(file));
-	return error;
+	return 0;
 }
 
 static int scm_max_fds(struct msghdr *msg)