Redfish: Hardcoded managers id was renamed to ${MANAGER_ID}

Changes:
    - In Apply DHCP Config Keyword Managers id was hardcoded as bmc
    - Renamed hardcoded value to ${MANAGER_ID}

Tested:
     - Ran The Script Successfully

Change-Id: I1870507682d209a15ae0ad20c3b9a1edc6a26d60
Signed-off-by: ganesanb <ganesanb@ami.com>
diff --git a/redfish/managers/test_multiple_interfaces_dhcp.robot b/redfish/managers/test_multiple_interfaces_dhcp.robot
index 7555962..a9f5e17 100644
--- a/redfish/managers/test_multiple_interfaces_dhcp.robot
+++ b/redfish/managers/test_multiple_interfaces_dhcp.robot
@@ -95,11 +95,11 @@
 
     ${active_channel_config}=  Get Active Channel Config
     Redfish.Patch
-    ...  /redfish/v1/Managers/bmc/EthernetInterfaces/${active_channel_config['${CHANNEL_NUMBER}']['name']}/
+    ...  /redfish/v1/Managers/${MANAGER_ID}/EthernetInterfaces/${active_channel_config['${CHANNEL_NUMBER}']['name']}/
     ...  body={"DHCPv4":${property}}  valid_status_codes=[${HTTP_OK}, ${HTTP_NO_CONTENT}]
 
     ${resp}=  Redfish.Get
-    ...  /redfish/v1/Managers/bmc/EthernetInterfaces/${active_channel_config['${CHANNEL_NUMBER}']['name']}
+    ...  /redfish/v1/Managers/${MANAGER_ID}/EthernetInterfaces/${active_channel_config['${CHANNEL_NUMBER}']['name']}
     Verify Ethernet Config Property  ${property}  ${resp.dict["DHCPv4"]}