virtio_ring: Merge identical variables

The variables `total_sg` and `descs_used` have the same value. Replace
the few uses of `total_sg` with `descs_used` to simplify the situation.

Signed-off-by: Andrew Scull <ascull@google.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
1 file changed