The current ovs unplug codepath for Windows triggers an OVSDB port
delete command, which is applicable, and a linux netdev delete command,
which is not. This changes the unplug logic to skip the delete step.
Change-Id: Id7f81ae174d354e593d919813bdf7b3b97cbcd8b
Closes-Bug: #1798051
Signed-off-by: Jan Gutter <jan.gutter@netronome.com>