iommu/iova: Move fast alloc size roundup into alloc_iova_fast()

iommu/iova: Move fast alloc size roundup into alloc_iova_fast()

It really is a property of the IOVA rcache code that we need to alloc a
power-of-2 size, so relocate the functionality to resize into
alloc_iova_fast(), rather than the callsites.

Signed-off-by: John Garry <john.garry@huawei.com>
Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Xie Yongji <xieyongji@bytedance.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/1638875846-23993-1-git-send-email-john.garry@huawei.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>