[PATCH][SRU][focal:linux-azure] hv_netvsc: Fix race between VF offering and VF association message from host

[Tim Gardner]

BugLink: https://bugs.launchpad.net/bugs/1994974

SRU Justification

[Impact]

During vm boot, there might be possibility that vf registration call comes before the vf association from host to vm.

And this might break netvsc vf path, this is in order to prevent the same block vf registration until vf bind message comes from host.

[Test Plan]

Microsoft tested. Positive result.

[Where things could go wrong]

The 5.4 backport patch could hang waiting for a VF addition to complete.

[Other Info]

SF: #00347129