If you're currently monitoring the device via SNMP, and you can see other resources on the device, such as interfaces, routing tables, and so on, it's possible that the SolarWinds SNMP MIB database does not contain the OIDs for CPU usage for these devices. If this is the case, then you may need to look in to creating a custom poller (or universal device poller, in older Orion instances).
What you'd need to do, is find out what OID you need to monitor. This can be doing by performing an SNMPWalk to the device from your Orion server (there's a SNMPWalk.exe tool within the Orion install directory, default location being C:\Program Files (x86)\SolarWinds\Orion\).
Once you have successfully got the OID list from the device, you'll have to work out which one shows you CPU information, and then use this OID in a new Orion Poller, and assign this poller to your Huawei device.
This guide is for NPM 12.0.1:
and this shows how to do it if you're running the older versions:
Hope this helps! If you don't have any luck, I suggest you raise a ticket with support, and they'll fill in any blanks and help you get the metrics you need!
Let us know how you get on