npu2: Fix clearing the FIR bits
npu2: Fix clearing the FIR bits

FIR registers are SCOM-only so they cannot be accesses with the indirect
write, and yet we use SCOM-based addresses for these; fix this.

Signed-off-by: Alexey Kardashevskiy <ac1fc56530d7d037e1ea666f130daca22d72f964@ozlabs.ru>
Reviewed-By: Alistair Popple <e9adbcf81c8a36ccc628e09bc92d0e25e1c8e501@popple.id.au>
Reviewed-by: Andrew Donnellan <44ca8c041ed925606732b2a0f30e5b73c32761a8@linux.ibm.com>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.ibm.com>

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