Move getPortInfo to Redfish Utility

Plan to use getPortInfo() to get the SSH SerialConsole in the
ComputerSystem.
This commit moves the getPortInfo functionality into the redfish
utility.

Tested: manually tested on Witherspoon system, there is no change in
output. Run Redfish validator, no error found.

Before:

"HTTPS": {
  "Certificates": {
    "@odata.id": "/redfish/v1/Managers/bmc/NetworkProtocol/HTTPS/
Certificates"
  },
  "Port": 443,
  "ProtocolEnabled": true
},
"IPMI": {
  "Port": 623,
  "ProtocolEnabled": true
},
"SSH": {
  "Port": 22,
  "ProtocolEnabled": true
}

After:

"HTTPS": {
  "Certificates": {
    "@odata.id": "/redfish/v1/Managers/bmc/NetworkProtocol/HTTPS/
Certificates"
  },
  "Port": 443,
  "ProtocolEnabled": true
},
"IPMI": {
  "Port": 623,
  "ProtocolEnabled": true
},
"SSH": {
  "Port": 22,
  "ProtocolEnabled": true
}

Change-Id: I126827fbbecec59adcf630b88e31bc5ff8151588
Signed-off-by: Abhishek Patel <Abhishek.Patel@ibm.com>