linux-phytec-ti

powerpc/powernv: Use it_page_shift in TCE build

This makes use of iommu_table::it_page_shift instead of TCE_SHIFT and
TCE_RPN_SHIFT hardcoded values.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>