Documentation: s390: correct spelling

Correct spelling problems for Documentation/s390/ as reported
by codespell.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20230209071400.31476-16-rdunlap@infradead.org


Signed-off-by: Heiko Carstens <hca@linux.ibm.com>