staging: lustre: lprocfs: implement log2 using bitops

This patch implements log2 using fls.
Signed-off-by: Andrew Perepechko <andrew_perepechko@xyratex.com>
Reviewed-by: Alexander Boyko <Alexander_Boyko@xyratex.com>
Reviewed-by: alexander_zarochentsev@xyratex.com
Reviewed-by: Vitaly Fertman <Vitaly_Fertman@xyratex.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3496
Xyratex-bug-id: MRP-999
Reviewed-on: http://review.whamcloud.com/6757Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/obdclass/lprocfs_status.c

@@ -1472,10 +1472,10 @@ EXPORT_SYMBOL(lprocfs_oh_tally);
 
 void lprocfs_oh_tally_log2(struct obd_histogram *oh, unsigned int value)
 {
-	unsigned int val;
+	unsigned int val = 0;
 
-	for (val = 0; ((1 << val) < value) && (val <= OBD_HIST_MAX); val++)
-		;
+	if (likely(value != 0))
+		val = min(fls(value - 1), OBD_HIST_MAX);
 
 	lprocfs_oh_tally(oh, val);
 }