powerpc/eeh: Sync OPAL API with firmware

The patch synchronizes OPAL APIs between kernel and firmware. Also,
we starts to replace opal_pci_get_phb_diag_data() with the similar
opal_pci_get_phb_diag_data2() and the former OPAL API would return
OPAL_UNSUPPORTED from now on.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>