Busybox does not support ps -p so use pgrep

Upstream-Status: Inappropriate [embedded specific]
Based on changes from Diego Sueiro <Diego.Sueiro@arm.com>

Signed-off-by: Armin kuster <akuster808@gmail.com>

Index: kea-1.7.10/src/bin/keactrl/keactrl.in
===================================================================
--- kea-1.7.10.orig/src/bin/keactrl/keactrl.in
+++ kea-1.7.10/src/bin/keactrl/keactrl.in
@@ -137,8 +137,8 @@ check_running() {
     # Get the PID from the PID file (if it exists)
     get_pid_from_file "${proc_name}"
     if [ ${_pid} -gt 0 ]; then
-        # Use ps to check if PID is alive
-        ps -p ${_pid} 1>/dev/null
+        # Use pgrep and grep to check if PID is alive
+        pgrep -v 1 | grep ${_pid} 1>/dev/null
         retcode=$?
         if [ $retcode -eq 0 ]; then
             # No error, so PID IS ALIVE