datapath-windows: Move vport code from Datapath.c to Vport.c.

Plain code motion. No additional cleanup or refactoring peformed.

I'll be doing some code refactoring in subsequent patches.

Signed-off-by: Nithin Raju <nithin@vmware.com>
Acked-by: Sorin Vinturis <svinturis@cloudbasesolutions.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>