iommu/vt-d: Use put_pages_list

page->freelist is for the use of slab.  We already have the ability
to free a list of pages in the core mm, but it requires the use of a
list_head and for the pages to be chained together through page->lru.
Switch the Intel IOMMU and IOVA code over to using free_pages_list().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
[rm: split from original patch, cosmetic tweaks, fix fq entries]
Signed-off-by: Robin Murphy <robin.murphy@arm.com>