Verify PNOR Update: fix None pflash_cmd value

Fixed an error where pflash_cmd value is set to None if pflash doesn't
support skip parm.

Change-Id: I45821d894daaf460e0e944bf1065c65645159769
Signed-off-by: Michael Walsh <micwalsh@us.ibm.com>
diff --git a/lib/utils.robot b/lib/utils.robot
index a0c56b8..852989d 100755
--- a/lib/utils.robot
+++ b/lib/utils.robot
@@ -83,9 +83,10 @@
     # Error 100 opening ffs !
 
     ${stdout}  ${stderr}  ${rc}=
-    ...  BMC Execute Command  /usr/sbin/pflash -h | egrep skip  ignore_err=${1}
-    ${pflash_cmd}=  Run Keyword if  ${rc} == ${0}
-    ...  Catenate  SEPARATOR=  ${pflash_cmd}  --skip=4096
+    ...  BMC Execute Command  /usr/sbin/pflash -h | egrep -q skip
+    ...  ignore_err=${1}
+    ${pflash_cmd}=  Set Variable If  ${rc} == ${0}  ${pflash_cmd} --skip=4096
+    ...  ${pflash_cmd}
     ${pnor_info}=  BMC Execute Command  ${pflash_cmd}
     Should Not Contain Any  ${pnor_info}  Flash header not found  Error