Set system, chassis, and bmc as global variables

Changes:
  - Add SYSTEM_ID as a global variable and set to default value system
  - Replace redfish/v1/Systems/system to redfish/v1/Systems/SYSTEM_ID
  - Replace redfish/v1/Chassis/chassis to redfish/v1/Chassis/CHASSIS_ID
  - Replace redfish/v1/Managers/bmc to redfish/v1/Managers/MANAGER_ID

Tested:
  - Tested on sandbox with the changes with sample test run with
    sample test ID runs
    1. without SYSTEM_ID provided
    2. with -v SYSTEM_ID:system1
    3. with export SYSTEM_ID=""
    3. with export SYSTEM_ID="system2"

Change-Id: Ifc412b20038cef1eba632caaa6c300be328259bd
Signed-off-by: Wilson Suen <wilsons@supermicro.com>
Signed-off-by: George Keishing <gkeishin@in.ibm.com>
diff --git a/lib/redfish_code_update_utils.robot b/lib/redfish_code_update_utils.robot
index 4395ef2..96dd265 100644
--- a/lib/redfish_code_update_utils.robot
+++ b/lib/redfish_code_update_utils.robot
@@ -24,7 +24,7 @@
     ...   '${image_info["Description"]}' == 'BMC image' or '${image_info["Description"]}' == 'BMC update'
     ...    Redfish.Get Attribute  /redfish/v1/Managers/${MANAGER_ID}  FirmwareVersion
     ...  ELSE
-    ...    Redfish.Get Attribute  /redfish/v1/Systems/system  BiosVersion
+    ...    Redfish.Get Attribute  /redfish/v1/Systems/${SYSTEM_ID}  BiosVersion
 
     ${functional}=  Run Keyword And Return Status
     ...   Should Be Equal  ${sw_functional}  ${image_info["Version"]}
@@ -245,7 +245,7 @@
     # quiet    Indicates whether results should be printed.
 
     ${state}=  Redfish.Get Attribute
-    ...  ${REDFISH_BASE_URI}Systems/system  PowerState
+    ...  ${REDFISH_BASE_URI}Systems/${SYSTEM_ID}  PowerState
     Rqprint Vars  state
 
     [Return]  ${state}