iommu/amd: Fix typo in macro parameter name

IVRS_GET_SBDF_ID is only called with fn as the fourth parameter,
so this had no effect, but fixing the name will avoid bugs if that
ever changes.

Signed-off-by: Michael Forney <mforney@mforney.org>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Link: https://lore.kernel.org/r/381fbc430c0ccdd78b3b696cfc0c32b233526ca5.1669159392.git.mforney@mforney.org


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