[SPARC64]: Fix kernel_thread() return value check in envctrl.c

drivers/sbus/char/envctrl.c

@@ -1140,7 +1140,7 @@ static int __init envctrl_init(void)
 	}
 
 	err = kernel_thread(kenvctrld, NULL, CLONE_FS | CLONE_FILES);
-	if (err)
+	if (err < 0)
 		goto out_deregister;
 
 	return 0;