Don't load powernv ipmi driver on non-power systems

[Jeff Lane ]

Verifying kernel modules:
- ipmi_si already loaded
- ipmi_devintf already loaded
* Unable to load module ipmi_powernv!
  **********************************************
  Warning: proceeding, but in-band IPMI may fail
  **********************************************
- ipmi_ssif already loaded
- ipmi_msghandler already loaded

currently we just blindly load all the drivers, but this triggers an unnecessary adn scary warning message in the output. Unless we're really running on ppc, do we really even need to attempt loading this driver?

No... we should not.