iommu/vt-d: Clean up unused PASID updating functions

iommu/vt-d: Clean up unused PASID updating functions

update_pasid() and its call chain are currently unused in the tree because
Thomas disabled the ENQCMD feature. The feature will be re-enabled shortly
using a different approach and update_pasid() and its call chain will not
be used in the new approach.

Remove the useless functions.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/20210920192349.2602141-1-fenghua.yu@intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20211014053839.727419-8-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>