Add correct response code for invalid certificate update

Changes:
For invalid certificate update via Redfish
expect return error code that is 400 -- Bad Request

Tested:
Verified with sanity run

Change-Id: I18ca7f105378dac8818be4f76ba2dc84acbf9ea9
Signed-off-by: Sridevi Ramesh <sridevra@in.ibm.com>
diff --git a/lib/certificate_utils.robot b/lib/certificate_utils.robot
index 6aeec22..412d677 100755
--- a/lib/certificate_utils.robot
+++ b/lib/certificate_utils.robot
@@ -236,7 +236,7 @@
     ...  CertificateType=PEM  CertificateUri=${certificate_dict}
 
     ${expected_resp}=  Set Variable If  '${expected_status}' == 'ok'  ${HTTP_OK}, ${HTTP_NO_CONTENT}
-    ...  '${expected_status}' == 'error'  ${HTTP_NOT_FOUND}, ${HTTP_INTERNAL_SERVER_ERROR}
+    ...  '${expected_status}' == 'error'  ${HTTP_NOT_FOUND}, ${HTTP_INTERNAL_SERVER_ERROR}, ${HTTP_BAD_REQUEST}
     ${resp}=  redfish.Post  /redfish/v1/CertificateService/Actions/CertificateService.ReplaceCertificate
     ...  body=${payload}  valid_status_codes=[${expected_resp}]