oem_ibm: Tie up the pvm_system_name with the AssetTag

- This commit would add the support for binding both the
  pvm_system_name bios attribute to redfish AssetTag.

Tested :

1. Change the bios attribute & make sure the AssetTag is updated.
2. Change the AssetTag and make sure the bios attribute is updated.

Signed-off-by: Manojkiran Eda <manojkiran.eda@gmail.com>
Change-Id: Ifef3abb56a6826304ce292c5ef1609f0740d5bdd
diff --git a/oem/ibm/configurations/bios/string_attrs.json b/oem/ibm/configurations/bios/string_attrs.json
index f928f2f..2e79920 100644
--- a/oem/ibm/configurations/bios/string_attrs.json
+++ b/oem/ibm/configurations/bios/string_attrs.json
@@ -8,7 +8,14 @@
          "default_string_length" : 0,
          "default_string" : "",
          "helpText" : "pvm_system_name",
-         "displayName" : "pvm_system_name"
+         "displayName" : "pvm_system_name",
+         "dbus":
+            {
+               "object_path" : "/xyz/openbmc_project/inventory/system",
+               "interface" : "xyz.openbmc_project.Inventory.Decorator.AssetTag",
+               "property_name" : "AssetTag",
+               "property_type" : "string"
+            }
       },
       {
          "attribute_name" : "vmi_hostname",