[PATCH] nvme/pci: Fix HMB size calculation

[hch@lst.de (Christoph Hellwig)]

On Mon, Jul 17, 2017@07:45:39PM -0400, Keith Busch wrote:
> It's possible the preferred HMB size may not be a multiple of the
> chunk_size. This patch will set the chunk_size to the descriptor's actual
> length so the last iteration doesn't cause the total size to exceed the
> allocated HMB size.

This looks a little weird, and might do the wrong thing
if we hit the retry loop after reducing chunk_size.

I suspect we just need to change to

	for (size = 0; size < preferred; size += len) {

and move len to function scope.