iommu: Do not export iommu_device_link/unlink()

These are not used outside iommu.c, they should not be available to
modular code.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/7-v3-328044aa278c+45e49-iommu_probe_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: jgunthorpe

drivers/iommu/iommu-sysfs.c

@@ -119,11 +119,9 @@ int iommu_device_link(struct iommu_device *iommu, struct device *link)
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(iommu_device_link);
 
 void iommu_device_unlink(struct iommu_device *iommu, struct device *link)
 {
 	sysfs_remove_link(&link->kobj, "iommu");
 	sysfs_remove_link_from_group(&iommu->dev->kobj, "devices", dev_name(link));
 }
-EXPORT_SYMBOL_GPL(iommu_device_unlink);