iommu: Change iommu_iotlb_gather to use iommu_page_list

iommu: Change iommu_iotlb_gather to use iommu_page_list

This converts the remaining places using list of pages to the new API.

The Intel free path was shared with its gather path, so it is converted at
the same time.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/11-v4-c8663abbb606+3f7-iommu_pages_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>