Fix "ps" in the code.

Recent kernel changes have removed the "-ef" option from "ps".

Impacted test BMC core dump is tested on both old and new kernel
and works clean.

Resolves  openbmc/openbmc-test-automation#1415

Change-Id: Ia1eef3e82355b588782ab6148acaa9b280517c63
Signed-off-by: George Keishing <gkeishin@in.ibm.com>
diff --git a/lib/dump_utils.robot b/lib/dump_utils.robot
index 23bf0dd..7551e7d 100644
--- a/lib/dump_utils.robot
+++ b/lib/dump_utils.robot
@@ -122,7 +122,7 @@
     [Documentation]  Trigger core dump.
 
     # Find the pid of the active ipmid and kill it.
-    ${cmd_buf}=  Catenate  kill -s SEGV $(ps -ef | egrep ' ipmid$' |
+    ${cmd_buf}=  Catenate  kill -s SEGV $(ps | egrep ' ipmid$' |
     ...  egrep -v grep | \ cut -c1-6)
 
     ${cmd_output}  ${stderr}  ${rc}=  BMC Execute Command  ${cmd_buf}