powerpc/eeh: Cleanup function names in the EEH core

The EEH has been implemented on pSeries platform. The original
code looks a little bit nasty. The patch does cleanup on the
current EEH implementation so that it looks more clean.

        * Try adding prefix "eeh" for functions.
        * Some function names have been adjusted so that they looks
          shorter and meaningful.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>