s390/mm: make pmd/pud_bad() report large entries as bad

s390/mm: make pmd/pud_bad() report large entries as bad

The semantics of pmd/pud_bad() expect that large entries are reported as
bad, but we also check large entries for sanity.

There is currently no issue with this wrong behaviour, but let's conform
to the semantics by reporting large pmd/pud entries as bad, in order to
prevent future issues.

This was found by testing a patch from from Anshuman Khandual, which is
currently discussed on LKML ("mm/debug: Add tests validating architecture
page table helpers").

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>