kernfs: fix typos in comments

Various spelling mistakes in comments.
Detected with the help of Coccinelle.

Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Link: https://lore.kernel.org/r/20220314115354.144023-5-Julia.Lawall@inria.fr


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>