iommu: Add iommu_copy_struct_from_user_array helper

Wrap up the data pointer/num sanity and __iommu_copy_struct_from_user()
call for iommu drivers to copy driver specific data at a specific location
in the struct iommu_user_data_array.

And expect it to be used in cache_invalidate_user ops for example.

Link: https://lore.kernel.org/r/20240111041015.47920-4-yi.l.liu@intel.com
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Co-developed-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>