Fix typos in the slof folder

Found with the "codespell" utility. I kept "busses" which codespell
also complains about since it seems to be an old but still valid
plural of the word "bus".

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>