Add IPv4/Ipv6 default gateway properties on Ethernet interface

Currently, OpenBMC stack allows a single default gateway
for the system(default gateway property present in system config)
Latest kernel allows to configure multiple default gateways.
so its proposed OpenBMC D-bus interfaces to tie the gateway property
with the Ethernet interface schema instead of system configuration dbus
interfaces and discussed over OpenBmc mailing list.

Clients will be able to configure default gateway for each Ethernet interface.
clients will use dbus property on Ethernet interface instead of system config
interface.

Implementation:
https://gerrit.openbmc-project.xyz/c/openbmc/phosphor-networkd/+/34852

Signed-off-by: Ravi Teja <raviteja28031990@gmail.com>
Change-Id: I5d671cac5ec8ef4ccd8deac0c0626e8d52db70eb
diff --git a/xyz/openbmc_project/Network/EthernetInterface.interface.yaml b/xyz/openbmc_project/Network/EthernetInterface.interface.yaml
index 9d7dfe6..2c3c108 100644
--- a/xyz/openbmc_project/Network/EthernetInterface.interface.yaml
+++ b/xyz/openbmc_project/Network/EthernetInterface.interface.yaml
@@ -71,6 +71,21 @@
           boolean value is TRUE when the network cable is inserted, or there
           is a carrier signal. It is FALSE when the cable is unplugged, or the
           carrier signal is missing.
+    - name: DefaultGateway
+      type: string
+      description: >
+          Default IPv4 gateway of the ethernet interface.
+      errors:
+        - xyz.openbmc_project.Common.Error.InvalidArgument
+    - name: DefaultGateway6
+      type: string
+      description: >
+          Default IPv6 gateway of the ethernet interface.
+          For supported address formats refer RFC 2373.
+          Refer below man page for both v4 and v6 address format details
+          https://man7.org/linux/man-pages/man3/inet_pton.3.html
+      errors:
+        - xyz.openbmc_project.Common.Error.InvalidArgument
 
 enumerations:
     - name: LinkLocalConf