[PATCH] powerpc/pseries: Fix TCE building with 64k pagesize

Must adjust tcenum and npages by TCE_PAGE_FACTOR to convert between
64KB pages and TCE (4K) pages.  (This is done in other places, except
for this one location.)

Signed-off-by: Michal Ostrowski <mostrows at watson ibm com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>