Check if nic is up after sleep when trying to bring it up

[aswinrajamannar]

Proposed Commit Message

Azure: Check if interface is up after sleep when trying to bring it up

summary:

When bringing interface up by unbinding and then binding hv_netvsc driver, it might take a short delay after binding for the link to be up. So before trying unbind/bind again after sleep, check if the link is up. This is a corner case when a preprovisioned VM is reused and the NICs are hot-attached.

Test Steps

• Deploy savable Pre-provisioned VMs whose NICs get hot-attached when they get reprovisioned
• Reuse them for a multi-NIC VM. In some cases, this may show up as a delay for the VM to report ready because we aggressively unbind, bind and check of status immediately after the bind.

Checklist:

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly
• I have updated or added any documentation accordingly