Managers ID : Introduced variable to declare Managers ID in resource.robot and updated all the scripts in openbmc-test-automation

Changes:
    - Introduced ${MANAGER_ID} variable in resource.robot
    - Replaced all the Managers/bmc to Managers/${MANAGER_ID} across all the scripts
    - Also in data/variables.py updated chassis id for the few redfish uri.

Tested:
     - Ran All The Scripts Successfully

Change-Id: Iff3673aae27657e0799dec5cb94c1651a0cd5d18
Signed-off-by: ganesanb <ganesanb@ami.com>
Signed-off-by: George Keishing <gkeishin@in.ibm.com>
diff --git a/redfish/managers/test_multiple_interfaces_dhcp.robot b/redfish/managers/test_multiple_interfaces_dhcp.robot
index 35baaec..da4bfc6 100644
--- a/redfish/managers/test_multiple_interfaces_dhcp.robot
+++ b/redfish/managers/test_multiple_interfaces_dhcp.robot
@@ -54,7 +54,7 @@
 
     ${data}=  Set Variable If  ${dhcp_enabled} == ${False}  ${DISABLE_DHCP}  ${ENABLE_DHCP}
     ${resp}=  Redfish.Patch
-    ...  /redfish/v1/Managers/bmc/EthernetInterfaces/${interface}
+    ...  /redfish/v1/Managers/${MANAGER_ID}/EthernetInterfaces/${interface}
     ...  body=${data}  valid_status_codes=${valid_status_code}
 
 Suite Setup Execution