Prevent Bulk OvsDB Node read during ext-network creation.

Prevent Bulk OvsDB Node read during ext-network creation.

Description:
In KPI environment, The external Provider network of GRE type are
mistakenly configured with physical-network name(public) which is not
valid. The physical-network-name parameter is only valid for flat/vlan
provider type use-cases.

Check added to prevent this bulk read other provider network
type(gre/vxlan)

Change-Id: I6936b0f178681155aa33e03e838c892d269df882
Signed-off-by: Chetan Arakere Gowdru <chetan.arakere@altencalsoftlabs.com>