rhel: Ensure proper OVS kernel modules load after upgrade

rhel: Ensure proper OVS kernel modules load after upgrade

Add post install and post un-install scripts to make sure that the
openvswitch kernel modules are correctly written with the weak-modules
utility. This ensures that after an upgrade to a newer kernel the
correct openvswitch kernel modules from a previous installation will
be found by the depmod search path.

Suggested-by: Flavio Leitner <fbl@sysclose.org>
Signed-off-by: Greg Rose <gvrose8192@gmail.com>
Acked-by: Ansis Atteka <aatteka@ovn.org>
Acked-by: Flavio Leitner <fbl@sysclose.org>