drbd: cleanup: change "<= 0" to "== 0"

dt is unsigned so it's never less than zero.  We are calculating the
elapsed time, and that's never less than zero (unless there is a bug or
we invent time travel).  The comparison here is just to guard against
divide by zero bugs.
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>

drivers/block/drbd/drbd_proc.c

@@ -118,7 +118,7 @@ static void drbd_syncer_progress(struct drbd_conf *mdev, struct seq_file *seq)
 	/* mean speed since syncer started
 	 * we do account for PausedSync periods */
 	dt = (jiffies - mdev->rs_start - mdev->rs_paused) / HZ;
-	if (dt <= 0)
+	if (dt == 0)
 		dt = 1;
 	db = mdev->rs_total - rs_left;
 	dbdt = Bit2KB(db/dt);