ROCM to use instantaneous power over average when available

Change the way power is sampled for the ROCM backend to use instantaneous power measurements when available. This API call defaults to average power on boards that do not support instantaneous power readings according to the ROCM documentation:

https://rocmdocs.amd.com/projects/rocm_smi_lib/en/latest/doxygen/html/group__PowerQuer.html#ga5c6fcd74be46ae056526c96d1a3ac09b

I've tested this with ROCM 6.0.0 on DAS6 where it seems to work correctly.