[SCSI] hpsa: use find_first_zero_bit

Use find_first_zero_bit to find the first cleared bit in a memory region.

This also includes the following minor changes.
- Use bitmap_zero
- Reduce unnecessary atomic bitops usage

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/hpsa.c

@@ -579,21 +579,19 @@ static int hpsa_find_target_lun(struct ctlr_info *h,
 	int i, found = 0;
 	DECLARE_BITMAP(lun_taken, HPSA_MAX_DEVICES);
 
-	memset(&lun_taken[0], 0, HPSA_MAX_DEVICES >> 3);
+	bitmap_zero(lun_taken, HPSA_MAX_DEVICES);
 
 	for (i = 0; i < h->ndevices; i++) {
 		if (h->dev[i]->bus == bus && h->dev[i]->target != -1)
-			set_bit(h->dev[i]->target, lun_taken);
+			__set_bit(h->dev[i]->target, lun_taken);
 	}
 
-	for (i = 0; i < HPSA_MAX_DEVICES; i++) {
-		if (!test_bit(i, lun_taken)) {
-			/* *bus = 1; */
-			*target = i;
-			*lun = 0;
-			found = 1;
-			break;
-		}
+	i = find_first_zero_bit(lun_taken, HPSA_MAX_DEVICES);
+	if (i < HPSA_MAX_DEVICES) {
+		/* *bus = 1; */
+		*target = i;
+		*lun = 0;
+		found = 1;
 	}
 	return !found;
 }