Revise the System On And PL Disabled test

On Witherspoon, unlike previous systems, it is expected that
power levels can be set even if dcmi power enablement has been
disabled. Need to revise the System On And PL Disabled
test case to allow for this, and remove that TC from the
skip_test list.

Resolves openbmc/openbmc-test-automation#1040
Change-Id: Iea2a40b5018450d8fd024a3f4b511ecf4234e001
Signed-off-by: Steven Sombar <ssombar@us.ibm.com>
diff --git a/systest/test_power_capping.robot b/systest/test_power_capping.robot
index 3aa8d1e..f7535aa 100644
--- a/systest/test_power_capping.robot
+++ b/systest/test_power_capping.robot
@@ -68,8 +68,8 @@
     Run External IPMI Standard Command  ${cmd}
     ${power}=  Get DCMI Power Limit
 
-    Should Be True  ${power} == ${power_setting}
-    ...  msg=Could set power limit when power limiting deactivated.
+    Should Be True  ${power} == ${500}
+    ...  msg=Could not set power limit when power limiting deactivated.
 
 
 Escale Check Settings System On Then Off