powerpc/powernv: Handle compound PE in config accessors

The PCI config accessors check for PE frozen state and clear it if
EEH isn't functional. The patch handles compound PE in config accessors
if PHB supports it. For consistency, all PEs will be put into frozen
state if any one in compound group gets frozen by hardware.

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