Fix for CSR related tests in redfishtool certificate suite

Changes:
    - keybit_length is suppose to have interger value. So now setting
      keybit_length variable to an interger value of 2048.

Tested:
    - Ran below test cases from sandbox successfully
      Verify CSR Generation For Server Certificate Via Redfishtool
      Verify CSR Generation For Client Certificate Via Redfishtool

Change-Id: Ie364b9fe9bab461804f0c50ba2e39037f915c0cb
Signed-off-by: manashsarma <manashsarma@in.ibm.com>
diff --git a/redfish/dmtf_tools/test_redfishtool_certificate.robot b/redfish/dmtf_tools/test_redfishtool_certificate.robot
index f6bc373..18a2265 100644
--- a/redfish/dmtf_tools/test_redfishtool_certificate.robot
+++ b/redfish/dmtf_tools/test_redfishtool_certificate.robot
@@ -22,7 +22,7 @@
 ${root_cmd_args} =  SEPARATOR=
 ...  redfishtool raw -r ${OPENBMC_HOST}:${HTTPS_PORT} -u ${OPENBMC_USERNAME} -p ${OPENBMC_PASSWORD} -S Always
 ${invalid_value}  abc
-${keybit_length}  2048
+${keybit_length}  ${2048}
 
 *** Test Cases ***