Network: Add NotAllowed error for MAC Address

Writing MAC address will return this error when changing MAC address
is disabled in phosphor-networkd.

Change-Id: Ib1e1383567a62ac80158509411f830e66e91a226
Signed-off-by: Jiaqing Zhao <jiaqing.zhao@intel.com>
diff --git a/yaml/xyz/openbmc_project/Network/MACAddress.interface.yaml b/yaml/xyz/openbmc_project/Network/MACAddress.interface.yaml
index 5c9daa0..243770d 100644
--- a/yaml/xyz/openbmc_project/Network/MACAddress.interface.yaml
+++ b/yaml/xyz/openbmc_project/Network/MACAddress.interface.yaml
@@ -11,3 +11,4 @@
       errors:
         - xyz.openbmc_project.Common.Error.InvalidArgument
         - xyz.openbmc_project.Common.Error.InternalFailure
+        - xyz.openbmc_project.Common.Error.NotAllowed