Add energy scale test case to skip list.

Add a test case to the skip list:
 Escale_System_On_And_PL_Disabled in systest/test_power_capping.robot.
This TC will fail until openbmc/openbmc#2379 is resolved.

Resolves  openbmc/openbmc-test-automation#1021
Change-Id: I5cfaa69eefc432ac30126d1632cabe307f0013f2
Signed-off-by: Steven Sombar <ssombar@us.ibm.com>
diff --git a/test_lists/skip_test_witherspoon b/test_lists/skip_test_witherspoon
index 645e4d4..be28912 100644
--- a/test_lists/skip_test_witherspoon
+++ b/test_lists/skip_test_witherspoon
@@ -32,3 +32,5 @@
 -e User_Management
 # NA test case for Witherspoon
 -e Verify_Channel_Checkstop_Through_OS_With_Auto_Reboot
+# https://github.com/openbmc/openbmc-test-automation/issues/1021
+-e Escale_System_On_And_PL_Disabled