/** \brief DHCP Proxy config add / del request
@param client_index - opaque cookie to identify the sender
/** \brief DHCP Proxy config add / del request
@param client_index - opaque cookie to identify the sender
@param is_add - add the config if non-zero, else delete
@param want_dhcp_event - DHCP event sent to the sender
via dhcp_compl_event API message if non-zero
@param is_add - add the config if non-zero, else delete
@param want_dhcp_event - DHCP event sent to the sender
via dhcp_compl_event API message if non-zero