iommu/amd: Remove EXPORT_SYMBOL for perf counter related functions

.. as IOMMU perf counters are always built as part of kernel.

No functional change intended.

Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Reviewed-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20240118090105.5864-7-vasant.hegde@amd.com


Signed-off-by: Joerg Roedel <jroedel@suse.de>