powerpc/powernv: Print correct PHB type names

We're initializing "IODA1" and "IODA2" PHBs though they are IODA2
and NPU PHBs as below kernel log indicates.

   Initializing IODA1 OPAL PHB /pciex@3fffe40700000
   Initializing IODA2 OPAL PHB /pciex@3fff000400000

This fixes the PHB names. After it's applied, we get:

   Initializing IODA2 PHB (/pciex@3fffe40700000)
   Initializing NPU PHB (/pciex@3fff000400000)

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>