iommu/arm-smmu-v3: Import IOMMUFD module namespace

Commit 69d9b31 ("iommu/arm-smmu-v3: Support IOMMU_VIOMMU_ALLOC")
started using _iommufd_object_alloc() without importing the IOMMUFD
module namespace, resulting in a modpost warning:

  WARNING: modpost: module arm_smmu_v3 uses symbol _iommufd_object_alloc from namespace IOMMUFD, but does not import it.

Commit d68beb2 ("iommu/arm-smmu-v3: Support IOMMU_HWPT_INVALIDATE
using a VIOMMU object") added another warning by using
iommufd_viommu_find_dev():

  WARNING: modpost: module arm_smmu_v3 uses symbol iommufd_viommu_find_dev from namespace IOMMUFD, but does not import it.

Import the IOMMUFD module namespace to resolve the warnings.

Fixes: 69d9b31 ("iommu/arm-smmu-v3: Support IOMMU_VIOMMU_ALLOC")
Link: https://patch.msgid.link/r/20241114-arm-smmu-v3-import-iommufd-module-ns-v1-1-c551e7b972e9@kernel.org
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c

@@ -397,3 +397,5 @@ struct iommufd_viommu *arm_vsmmu_alloc(struct device *dev,
 
 	return &vsmmu->core;
 }
+
+MODULE_IMPORT_NS(IOMMUFD);