Fix scom addresses for power9 nx checkstop hmi handling.
Fix scom addresses for power9 nx checkstop hmi handling.

Scom addresses for NX status, DMA & ENGINE FIR and PBI FIR has changed
for Power9. Fixup thoes while handling nx checkstop for Power9.

Signed-off-by: Mahesh Salgaonkar <6a890e1065a1d4e8df9dcf1d9a2c9c740bbcf8aa@linux.vnet.ibm.com>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

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