iommufd/selftest: Fix _test_mock_dirty_bitmaps()

mainline inclusion
from mainline-v6.7-rc5
commit 98594181944daa201481ad63242806beb7c89ff4
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/?98594181944daa201481ad63242806beb7c89ff4

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

The ASSERT_EQ() macro sneakily expands to two statements, so the loop here
needs braces to ensure it captures both and actually terminates the test
upon failure. Where these tests are currently failing on my arm64 machine,
this reduces the number of logged lines from a rather unreasonable
~197,000 down to 10. While we're at it, we can also clean up the
tautologous "count" calculations whose assertions can never fail unless
mathematics and/or the C language become fundamentally broken.

Intel-SIG: 98594181944d iommufd/selftest: Fix _test_mock_dirty_bitmaps()
Backport IOMMUFD Dirty Tracking

Fixes: a9af47e382a4 ("iommufd/selftest: Test IOMMU_HWPT_GET_DIRTY_BITMAP")
Link: https://lore.kernel.org/r/90e083045243ef407dd592bb1deec89cd1f4ddf2.1700153535.git.robin.murphy@arm.com


Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Tested-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
[ jz: amend commit log ]
Signed-off-by: Jason Zeng <jason.zeng@intel.com>