powerpc/eeh: Delete an error out of memory message at init time

Omit an extra message for a memory allocation failure in
eeh_dev_init().

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
[mpe: Do not drop the message that can happen at runtime and lead to
 an event not being handled]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>