powerpc/powernv: Remove unused file

The patch removes unused file eeh-ioda.c and updates makefile
accordingly. Besides, the definition of "struct pnv_eeh_ops" and
the instances are all removed. Until now, the chip layer of EEH
implementation for PowerNV platform is removed completely.

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