virtio_ring: use helper function is_power_of_2()

Use helper function is_power_of_2() to check if num is power of two.
Minor readability improvement.
Signed-off-by: NShaoqin Huang <shaoqin.huang@intel.com>
Message-Id: <20221021062734.228881-3-shaoqin.huang@intel.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NXuan Zhuo <xuanzhuo@linux.alibaba.com>

drivers/virtio/virtio_ring.c

@@ -1052,7 +1052,7 @@ static int vring_alloc_queue_split(struct vring_virtqueue_split *vring_split,
 	dma_addr_t dma_addr;
 
 	/* We assume num is a power of 2. */
-	if (num & (num - 1)) {
+	if (!is_power_of_2(num)) {
 		dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num);
 		return -EINVAL;
 	}