s390/mm: add missing conversion to use ptdescs

Commit 6326c26c ("s390: convert various pgalloc functions
to use ptdescs") missed to convert tlb_remove_table() into
tlb_remove_ptdesc() in few locations.

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>