Automatically find first unlocked user slot

Instead of relying on hard coded offsets, query each slot's status with ```ipmitool channel getaccess``` and use the first slot that is unlocked.

This fixes an issue on certain Cray x86 nodes that have arbitrary locked IPMI user slots.

xCAT-genesis-scripts/usr/bin/bmcsetup

@@ -429,6 +429,14 @@ for user in $BMCUS; do
         USERSLOT=$((`ipmitool raw 6 0x44 1 1|awk '{print $3}'` + 1))
     fi
     if [ "$USERSLOT" == 0 -o -z "$LOCKEDUSERS" ]; then USERSLOT=2; fi
+    # automatically find first unlocked user slot
+    for slot in {1..16}; do
+        USERLOCKED=`ipmitool channel getaccess $LANCHAN $slot | grep Fixed | awk '{print $4}'`
+        if [ "$USERLOCKED" == "No" ]; then
+            USERSLOT=$slot
+            break
+        fi
+    done
     if [ "$ISITE" = 1 ]; then
         allowcred.awk &
         CREDPID=$!