AWS volumes: Use /dev/xvdXX names with EC2
AWS volumes: Use /dev/xvdXX names with EC2

We are using HVM style names, which cannot be paravirtual style names.

See
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/device_naming.html

This also fixes problems introduced when moving volume mounting to KCM.

Fix #27534

kubernetes/cloud-provider-aws,kubernetes/cloud-provider-aws,kubernetes/cloud-provider-aws