fs: namei: Fix spelling mistake "Retuns" to "Returns"

There are two spelling mistake in comments. Fix it.

Signed-off-by: YangXin <yx.0xffff@gmail.com>
Link: https://lore.kernel.org/r/20231118132136.3084-1-yx.0xffff@gmail.com


Signed-off-by: Christian Brauner <brauner@kernel.org>