support xcat genesis on ppc64: check if the dmidecode exists before run dmidecode

xCAT-genesis-scripts/bin/doxcat

@@ -176,9 +176,11 @@ ntpd -g -x
 # rv 0 state does not work with the new ntp versions
 #(while ! ntpq -c "rv 0 state"|grep 'state=4' > /dev/null; do sleep 1; done; hwclock --systohc) &
 (while [ "`ntpq -c \"rv 0 offset\" | grep \"offset=\" | awk -F \"=\" '{print $2}' | awk -F \".\" '{print $1}' | sed s/-//`" -ge 1000 ]; do sleep 1; done; hwclock --systohc) &
-if dmidecode|grep IPMI > /dev/null; then
-	modprobe ipmi_si
-	modprobe ipmi_devintf
+if [ -f "/usr/sbin/dmidecode" ]; then
+    if dmidecode|grep IPMI > /dev/null; then
+        modprobe ipmi_si
+        modprobe ipmi_devintf
+    fi
 fi
 DEVICE=$bootnic
 export DEVICE