ovn-k8s-overlay: Create a function to configure management port.
ovn-k8s-overlay: Create a function to configure management port.

This commit does not add any new functionality but only moves
existing code to a new function.  The current code to configure
management port is Linux specific.  Having it in a separate function
helps to do more Linux specific things.

Signed-off-by: Gurucharan Shetty <a1872e333d0e52644f6125da2276530f7ebe5e77@ovn.org>

shettyg/ovn-kubernetes,shettyg/ovn-kubernetes,shettyg/ovn-kubernetes