iommu: Improve iopf_queue_remove_device()

iommu: Improve iopf_queue_remove_device()

Convert iopf_queue_remove_device() to return void instead of an error code,
as the return value is never used. This removal helper is designed to be
never-failed, so there's no need for error handling.

Ack all outstanding page requests from the device with the response code of
IOMMU_PAGE_RESP_INVALID, indicating device should not attempt any retry.

Add comments to this helper explaining the steps involved in removing a
device from the iopf queue and disabling its PRI. The individual drivers
are expected to be adjusted accordingly. Here we just define the expected
behaviors of the individual iommu driver from the core's perspective.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Yan Zhao <yan.y.zhao@intel.com>
Link: https://lore.kernel.org/r/20240212012227.119381-14-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>