powerpc/eeh: Escalate error on non-existing PE

Sometimes, especially in sinario of loading another kernel with kdump,
we got EEH error on non-existing PE. That means the PEEV / PEST in
the corresponding PHB would be messy and we can't handle that case.
The patch escalates the error to fenced PHB so that the PHB could be
rested in order to revoer the errors on non-existing PEs.

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