vtep: Initial checkin of vtep schema.

vtep: Initial checkin of vtep schema.

The hardware VTEP OVSDB schema specifies relations that a VTEP can use
to integrate physical ports into logical switches maintained by a
network virtualization controller such as NVP.

Co-authored-by: Ben Pfaff <blp@nicira.com>
Co-authored-by: Kenneth Duda <kduda@aristanetworks.com>
Co-authored-by: Justin Pettit <jpettit@nicira.com>
Signed-off-by: Bruce Davie <bdavie@vmware.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
Signed-off-by: Kenneth Duda <kduda@aristanetworks.com>
Signed-off-by: Justin Pettit <jpettit@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>