hyperv/hn: Apply VF's RSS setting

Since in Azure SYN and SYN|ACK go through the synthetic parts while the
rest of the same TCP flow goes through the VF, apply VF's RSS settings
to synthetic parts to have a consistent hash value/type for the same TCP
flow.

MFC after: 1 week
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D12333