powerpc/eeh: Fix missed PE#0 on P7IOC

PE#0 should be regarded as valid for P7IOC, while it's invalid for
PHB3. The patch adds flag EEH_VALID_PE_ZERO to differentiate those
two cases. Without the patch, we possibly see frozen PE#0 state is
cleared without EEH recovery taken on P7IOC as following kernel logs
indicate:

[root@ltcfbl8eb ~]# dmesg
       :
pci 0000:00     : [PE# 000] Secondary bus 0 associated with PE#0
pci 0000:01     : [PE# 001] Secondary bus 1 associated with PE#1
pci 0001:00     : [PE# 000] Secondary bus 0 associated with PE#0
pci 0001:01     : [PE# 001] Secondary bus 1 associated with PE#1
pci 0002:00     : [PE# 000] Secondary bus 0 associated with PE#0
pci 0002:01     : [PE# 001] Secondary bus 1 associated with PE#1
pci 0003:00     : [PE# 000] Secondary bus 0 associated with PE#0
pci 0003:01     : [PE# 001] Secondary bus 1 associated with PE#1
pci 0003:20     : [PE# 002] Secondary bus 32..63 associated with PE#2
       :
EEH: Clear non-existing PHB#3-PE#0
EEH: PHB location: U78AE.001.WZS00M9-P1-002

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/kernel/eeh_pe.c b/arch/powerpc/kernel/eeh_pe.c
index 5a63e2b0..fa950fb 100644
--- a/arch/powerpc/kernel/eeh_pe.c
+++ b/arch/powerpc/kernel/eeh_pe.c
@@ -239,10 +239,18 @@
 	if (pe->type & EEH_PE_PHB)
 		return NULL;
 
-	/* We prefer PE address */
-	if (edev->pe_config_addr &&
-	   (edev->pe_config_addr == pe->addr))
+	/*
+	 * We prefer PE address. For most cases, we should
+	 * have non-zero PE address
+	 */
+	if (eeh_has_flag(EEH_VALID_PE_ZERO)) {
+		if (edev->pe_config_addr == pe->addr)
+			return pe;
+	} else {
+		if (edev->pe_config_addr &&
+		    (edev->pe_config_addr == pe->addr))
 		return pe;
+	}
 
 	/* Try BDF address */
 	if (edev->config_addr &&