Add StaticNTPServers propetry to EthernetInterface

Currently there is no way to differentiate between the Static
and DHCP assigned NTP servers at dbus

This commit adds StaticNTPServers peroperty to hold the static
configuration of NTP servers. This is a read-write property.
The existing NTPServer propery will hold both static and DHCP
assigned NTP servers. This is a read-only property.

Signed-off-by: Sunitha Harish <sunharis@in.ibm.com>
Change-Id: If6ac588c268473802ebb1b8f08144df594ac943a
diff --git a/yaml/xyz/openbmc_project/Network/EthernetInterface.interface.yaml b/yaml/xyz/openbmc_project/Network/EthernetInterface.interface.yaml
index b86a10e..94ff988 100644
--- a/yaml/xyz/openbmc_project/Network/EthernetInterface.interface.yaml
+++ b/yaml/xyz/openbmc_project/Network/EthernetInterface.interface.yaml
@@ -49,10 +49,16 @@
           - xyz.openbmc_project.Common.Error.InvalidArgument
     - name: NTPServers
       type: array[string]
+      flags:
+          - readonly
       description: >
-          This property describes the NTP Servers on the interface.
-          Implementation of this Dbus-interface is required to implement this property.
-          This property supports read/write operation.
+          NTP servers that are currently in use on this interface.
+          This includes both DHCP and static NTP server addresses.
+    - name: StaticNTPServers
+      type: array[string]
+      description: >
+          This property describes statically defined NTPServers on the
+          interface. This property supports read/write operation.
           Configure the NTP servers on the system during write operation.
     - name: LinkLocalAutoConf
       type: enum[self.LinkLocalConf]