iommu/vt-d: Remove unused function declarations

Some functions have been removed. Remove the remaining function
delarations.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210323010600.678627-5-baolu.lu@linux.intel.com


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