phb4: Don't try to access non-existent PEST entries
phb4: Don't try to access non-existent PEST entries

In a POWER9 chip, some PHB4s have 256 PEs, some have 512.

Currently, the diagnostics code retrieves 512 unconditionally,
which is wrong and causes us to incorrectly report bogus values
for the "high" PEs on the small PHBs.

Use the actual number of implemented PEs instead

Signed-off-by: Benjamin Herrenschmidt <a7089bb6e7e92505d88aaff006cbdd60cc9120b6@kernel.crashing.org>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

shenki/skiboot,open-power/skiboot,shenki/skiboot,stewart-ibm/skiboot,shenki/skiboot,qemu/skiboot,stewart-ibm/skiboot,legoater/skiboot,open-power/skiboot,open-power/skiboot,shenki/skiboot,qemu/skiboot,legoater/skiboot,qemu/skiboot,stewart-ibm/skiboot,shenki/skiboot,qemu/skiboot,legoater/skiboot,open-power/skiboot,open-power/skiboot,qemu/skiboot,legoater/skiboot,legoater/skiboot