FROMLIST: iommu: arm: fix building smmuv3 as loadable module

The smmu-v3 kunit test fail to link when the SMMU driver is configured
as a loadable mdoule:

ERROR: modpost: "arm_smmu_make_cdtable_ste" [drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.ko] undefined!
ERROR: modpost: "arm_smmu_make_s2_domain_ste" [drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.ko] undefined!
ERROR: modpost: "arm_smmu_make_s1_cd" [drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.ko] undefined!
ERROR: modpost: "arm_smmu_make_bypass_ste" [drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.ko] undefined!
ERROR: modpost: "arm_smmu_make_abort_ste" [drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.ko] undefined!
ERROR: modpost: "arm_smmu_make_sva_cd" [drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.ko] undefined!
ERROR: modpost: "arm_smmu_get_ste_used" [drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.ko] undefined!
ERROR: modpost: "arm_smmu_write_entry" [drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.ko] undefined!
ERROR: modpost: "arm_smmu_get_cd_used" [drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.ko] undefined!

The problem is that the drivers/iommu/arm/arm-smmu-v3/Makefile only gets
parsed while building modules, but the driver itself is accidentally marked
as built-in unconditionally, so not only does the kunit test fail, but the
entire driver is missing.

Change the driver configuration back to $(CONFIG_ARM_SMMU_V3) so it
actually gets build here.

Fixes: e436576b ("iommu: make inclusion of arm/arm-smmu-v3 directory conditional")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Link: https://lore.kernel.org/all/20250523121257.2340274-1-arnd@kernel.org/


Change-Id: I66b91ed8d52123676ff7039ec1827fcf1b725487
Signed-off-by: Carlos Llamas <cmllamas@google.com>