s390/pgtable: Switch read and write softbits for puds

There is no reason for the read and write softbits to be swapped in the
puds compared to pmds. They are different only because the softbits for
puds were introduced at the same time when the softbits for pmds were
swapped.

The current implementation is not wrong per se, since the macros are
defined correctly; only the documentation does not reflect reality.

With this patch, the read and write softbits for large pmd and large
puds will have the same layout, and will match the existing
documentation.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20240429143409.49892-2-imbrenda@linux.ibm.com


Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>