powerpc/powernv/ioda2: Move TCE kill register address to PE

At the moment the DMA setup code looks for the "ibm,opal-tce-kill"
property which contains the TCE kill register address. Writing to
this register invalidates TCE cache on IODA/IODA2 hub.

This moves the register address from iommu_table to pnv_pnb as this
register belongs to PHB and invalidates TCE cache for all tables of
all attached PEs.

This moves the property reading/remapping code to a helper which is
called when DMA is being configured for PE and which does DMA setup
for both IODA1 and IODA2.

This adds a new pnv_pci_ioda2_tce_invalidate_entire() helper which
invalidates cache for the entire table. It should be called after
every call to opal_pci_map_pe_dma_window(). It was not required before
because there was just a single TCE table and 64bit DMA was handled via
bypass window (which has no table so no cache was used) but this is going
to change with Dynamic DMA windows (DDW).

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>