powerpc/eeh/of: Checking for CONFIG_EEH is not needed

The functions used are already defined as empty inline functions for the
case where EEH is disabled.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>
Acked-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>