s390/mm: fix memory leak of ptlock in pmd_free_tlb

The pmd_free_tlb function fails to call pgtable_pmd_page_dtor.
Without the call the ptlock for the pmd tables will not be freed.
Add the missing call.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
1 file changed