iommufd/selftest: Prevent module/builtin conflicts in kconfig

The selftest now depends on the AMDv1 page table, however the selftest
kconfig itself is just an sub-option of the main IOMMUFD module kconfig.

This means it cannot be modular and so kconfig allowed a modular
IOMMU_PT_AMDV1 with a built in IOMMUFD. This causes link failures:

   ld: vmlinux.o: in function `mock_domain_alloc_pgtable.isra.0':
   selftest.c:(.text+0x12e8ad3): undefined reference to `pt_iommu_amdv1_init'
   ld: vmlinux.o: in function `BSWAP_SHUFB_CTL':
   sha1-avx2-asm.o:(.rodata+0xaa36a8): undefined reference to `pt_iommu_amdv1_read_and_clear_dirty'
   ld: sha1-avx2-asm.o:(.rodata+0xaa36f0): undefined reference to `pt_iommu_amdv1_map_pages'
   ld: sha1-avx2-asm.o:(.rodata+0xaa36f8): undefined reference to `pt_iommu_amdv1_unmap_pages'
   ld: sha1-avx2-asm.o:(.rodata+0xaa3720): undefined reference to `pt_iommu_amdv1_iova_to_phys'

Adjust the kconfig to disable IOMMUFD_TEST if IOMMU_PT_AMDV1 is incompatible.

Fixes: e93d5945 ("iommufd: Change the selftest to use iommupt instead of xarray")
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202512210135.freQWpxa-lkp@intel.com/


Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>