iommufd/selftest: Remove MOCK_IOMMUPT_AMDV1 format

iommufd/selftest: Remove MOCK_IOMMUPT_AMDV1 format

syzbot found that allocating a mock domain with AMDV1 format could
cause a WARN_ON because the selftest enabled DYNAMIC_TOP without
providing the required driver_ops.

The AMDV1 format in the selftest was a placeholder and was not actually
used by any of the existing selftests. Instead of adding dummy
driver_ops to satisfy the requirements of a format we don't currently
test, remove the AMDV1 format option from the selftest.

The MOCK_IOMMUPT_DEFAULT and MOCK_IOMMUPT_HUGE formats are unaffected as
they use the amdv1_mock variant which does not enable DYNAMIC_TOP.

Fixes: dcd6a011a8d5 ("iommupt: Add map_pages op")
Link: https://patch.msgid.link/r/20260330092609.2659235-1-praan@google.com
Reported-by: syzbot+453eb7add07c3767adab@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/69c1d50b.a70a0220.3cae05.0001.GAE@google.com/
Signed-off-by: Pranjal Shrivastava <praan@google.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>