powerpc/powernv/pci: Remove SWINV constants and obsolete TCE code

We have some obsolete code in pnv_pci_p7ioc_tce_invalidate()
to handle some internal lab tools that have stopped being
useful a long time ago. Remove that along with the definition
and test for the TCE_PCI_SWINV_* flags whose value is basically
always the same.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>