powerpc/pseries: Enable an interface to represent PAPR firmware attributes

Description: Enhancement to Sensors to provide platform information in PowerVM.

Bugzilla: http://bugzilla.redhat.com/1869665

Build Info: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=44269405

Tested: Successfully tested by IBM. Sanity boot tested on power 9 (ibm-p9z-16-lp13) system.

Signed-off-by: Steve Best sbest@redhat.com