npu2: hw-procedures: Refactor reset_ntl procedure
npu2: hw-procedures: Refactor reset_ntl procedure

Change the implementation of reset_ntl to match the latest programming
guide documentation.

Signed-off-by: Reza Arbab <4c896a97e6b998365c2d50a267b0f1ca5f7995de@linux.vnet.ibm.com>
Reviewed-by: Balbir Singh <ac7b77b73f9d2cc0faddd296218dde0558e170e3@gmail.com>
Reviewed-by: Alistair Popple <e9adbcf81c8a36ccc628e09bc92d0e25e1c8e501@popple.id.au>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

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