staging: lustre: workitem.c: replace IS_PO2 by is_power_of_2

Replaces IS_PO2 by is_power_of_2. It is more accurate to use
is_power_of_2 since it returns 1 for numbers that are powers
of 2 only whereas IS_PO2 returns 1 for 0 and numbers that are
powers of 2.
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Aya Mahfouz <mahfouz.saif.elyazal@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/libcfs/workitem.c

@@ -325,7 +325,7 @@ cfs_wi_sched_destroy(struct cfs_wi_sched *sched)
 
 	spin_lock(&cfs_wi_data.wi_glock);
 	while (sched->ws_nthreads > 0) {
-		CDEBUG(IS_PO2(++i) ? D_WARNING : D_NET,
+		CDEBUG(is_power_of_2(++i) ? D_WARNING : D_NET,
 		       "waiting for %d threads of WI sched[%s] to terminate\n",
 		       sched->ws_nthreads, sched->ws_name);