powerpc/eeh: Avoid event on passed PE

We must not handle EEH error on devices which are passed to somebody
else. Instead, we expect that the frozen device owner detects an EEH
error and recovers from it.

This avoids EEH error handling on passed through devices so the device
owner gets a chance to handle them.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Acked-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>