Rename descriptions of the supported ENA devices

Some of the PCI ID were described as ENA with LLQ support - it's not
fully accurate and because of that, their names were changed.

Instead of LLQ, use RSERV0 for the description of those devices.

Submitted by: Michal Krawczyk <mk@semihalf.com>
Obtained from: Semihalf
Sponsored by: Amazon, Inc
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D27119