Fix the psushow error message on platorm without psu at all

[yuazhe]

What I did

de-escalate the message when no psu had been detected at all from error to more moderate info.

How I did it

simply change the print output and remove the redundance ones

How to verify it

UT as well as manual test

Previous command output (if the output of a command-line utility has changed)

Error: Failed to get the number of PSUs
Error: Failed to get PSU status
Error: failed to get PSU status from state DB

New command output (if the output of a command-line utility has changed)

PSU not detected

[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).