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/openpower/pel/test_bmc_pel.robot b/openpower/pel/test_bmc_pel.robot
index ec51e45..5ba76a6 100644
--- a/openpower/pel/test_bmc_pel.robot
+++ b/openpower/pel/test_bmc_pel.robot
@@ -165,9 +165,9 @@
     #    [Serial Number]:                              ABCDEFG    <---- Serial number
     #    [Sub-section type]:                           0
 
-    ${redfish_machine_model}=  Redfish.Get Attribute  /redfish/v1/Systems/system/  Model
+    ${redfish_machine_model}=  Redfish.Get Attribute  /redfish/v1/Systems/${SYSTEM_ID}/  Model
     ${redfish_machine_model}=  Replace String Using Regexp  ${redfish_machine_model}  ^0+  ${EMPTY}
-    ${redfish_serial_number}=  Redfish.Get Attribute  /redfish/v1/Systems/system/  SerialNumber
+    ${redfish_serial_number}=  Redfish.Get Attribute  /redfish/v1/Systems/${SYSTEM_ID}/  SerialNumber
     ${redfish_serial_number}=  Replace String Using Regexp  ${redfish_serial_number}  ^0+  ${EMPTY}
 
     Valid Value  pel_machine_type_model  ['${redfish_machine_model}']
@@ -267,7 +267,7 @@
     #    [BMC Event Log Id]:           341      <---- BMC event log id value
     #    [Committed at]:               03/25/1920 12:06:22
 
-    ${redfish_event_logs}=  Redfish.Get Properties  /redfish/v1/Systems/system/LogServices/EventLog/Entries
+    ${redfish_event_logs}=  Redfish.Get Properties  /redfish/v1/Systems/${SYSTEM_ID}/LogServices/EventLog/Entries
 
     # Example of redfish_event_logs output:
     # redfish_event_logs: