get_file_rcu(): no need to check for NULL separately

IS_ERR(NULL) is false and IS_ERR() already comes with unlikely()...

Reviewed-by: Christian Brauner <[e-mail]>
Signed-off-by: Al Viro <[e-mail]>

fs/file.c

···
 		struct file __rcu *file;
 
 		file = __get_file_rcu(f);
-		if (unlikely(!file))
-			return NULL;
-
-		if (unlikely(IS_ERR(file)))
-			continue;
-
-		return file;
+		if (!IS_ERR(file))
+			return file;
 	}
 }
 EXPORT_SYMBOL_GPL(get_file_rcu);