quickstart: do not bind Mellanox NICs to Linux driver

The Mellanox NICs do not need binding to Linux driver.
Make this notice prominent to the users.

Signed-off-by: Jieqiang Wang <jieqiang.wang@arm.com>
Reviewed-by: Lijian Zhang <lijian.zhang@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>

Change-Id: I484257f4a2e1ce44177f1966db52b3acb57cf2b7