IB/mthca: Fix memory leak of multicast group structures

Convert "/ (1 << lg)" to ">> lg" for a slight code size reduction.

add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-24 (-24)
function                                     old     new   delta
mthca_map_cmd                                613     589     -24

Signed-off-by: Ishai Rabinovitz <ishai@mellanox.co.il>
Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/mthca/mthca_cmd.c

@@ -606,7 +606,7 @@ static int mthca_map_cmd(struct mthca_dev *dev, u16 op, struct mthca_icm *icm,
 			err = -EINVAL;
 			goto out;
 		}
-		for (i = 0; i < mthca_icm_size(&iter) / (1 << lg); ++i) {
+		for (i = 0; i < mthca_icm_size(&iter) >> lg; ++i) {
 			if (virt != -1) {
 				pages[nent * 2] = cpu_to_be64(virt);
 				virt += 1 << lg;