datapath-windows: Pause switch state on PnP event

datapath-windows: Pause switch state on PnP event

A PnP(plug and play) event will be triggered before trying to disable
the extension. We could use this PnP event to prepare for detaching
the datapath.

This patch sets the switch into a paused state so no more net buffers
are queued.

Also clean some commentaries.

Signed-off-by: Alin Gabriel Serdean <aserdean@cloudbasesolutions.com>
Acked-by: Sairam Venugopal <vsairam@vmware.com>
Acked-by: Nithin Raju <nithin@vmware.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>