Print information when ENA admin error occurs

ENA_ADMIN_FATAL_ERROR and ENA_ADMIN_WARNING aenq groups were indicated
as supported, so the unimplemented_aenq_handler() will print out error
message, whenever an error will occur within the ENA admin context.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Obtained from: Semihalf
Sponsored by: Amazon, Inc.