powerpc/eeh: Quieten EEH message when no adapters are found

No real need for this to be pr_warn(), reduce it to pr_info().

Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>