Fix session persistency check post reboot

With new option -v REDFISH_DELETE_SESSIONS:0 boot test no longer flush
the active sessions post bmc reset.

Change-Id: I6c9f2187cea951e2608328ce903314df1e421152
Signed-off-by: George Keishing <gkeishin@in.ibm.com>
diff --git a/redfish/service_root/test_sessions_management.robot b/redfish/service_root/test_sessions_management.robot
index e7a81cc..85d2d29 100644
--- a/redfish/service_root/test_sessions_management.robot
+++ b/redfish/service_root/test_sessions_management.robot
@@ -158,7 +158,6 @@
     ${session_location}=  Redfish.Get Session Location
 
     Redfish OBMC Reboot (off)  stack_mode=normal
-    Redfish.Login
 
     # Check for session persistency after BMC reboot.
     # sessions here will have list of all sessions location.