powerpc/powernv: Remove useless wrapper

This gets rid of a useless wrapper around
pnv_pci_ioda2_table_free_pages().

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>