iommufd/selftest: Iterate idev_ids in mock_domain's alloc_hwpt test

mainline inclusion
from mainline-v6.7-rc1
commit bb812e0069ce5de9af2a7910951c8c95632cebe3
category: feature
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I8Y6AM
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?bb812e0069ce5de9af2a7910951c8c95632cebe3

--------------------------------

The point in iterating variant->mock_domains is to test the idev_ids[0]
and idev_ids[1]. So use it instead of keeping testing idev_ids[0] only.

Intel-SIG: bb812e0069ce iommufd/selftest: Iterate idev_ids in mock_domain's alloc_hwpt test
Backport IOMMUFD Dirty Tracking

Link: https://lore.kernel.org/r/20230919011637.16483-1-nicolinc@nvidia.com


Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
[ jz: amend commit log ]
Signed-off-by: Jason Zeng <jason.zeng@intel.com>