linux_renameat2: don't add extra \n on error.

linux_msg() already adds \n at the end of all messages.

Reported by:	emaste, kib (mentor), mjg (mentor)
Reviewed by:	kib (mentor), mjg (mentor)
Differential Revision:	https://reviews.freebsd.org/D21852

sys/compat/linux/linux_file.c

@@ -704,7 +704,7 @@ linux_renameat2(struct thread *td, struct linux_renameat2_args *args)
 	int error, olddfd, newdfd;
 
 	if (args->flags != 0) {
-		linux_msg(td, "renameat2 unsupported flags 0x%x\n",
+		linux_msg(td, "renameat2 unsupported flags 0x%x",
 		    args->flags);
 		return (EINVAL);
 	}