x86: add support for AWS T3 instances

x86: add support for AWS T3 instances

Amazon AWS T3 cloud instances require kernel support
for the Elastic Fabric Adapter to access storage
and for Elastic Network Adapter to use network
interfaces.

Since the Fabric Adapter is needed to access
root filesystem, enable in x86_64 kernel.

Elastic Network Adapter goes in a module,
and add this module to default list in x86_64.
The module is set to AutoLoad because AutoProbe does
not seem to load it.

Signed-off-by: Alberto Bursi <bobafetthotmail@gmail.com>