iommu/vt-d: Remove BUG_ON in map/unmap()

Domain map/unmap with invalid parameters shouldn't crash the kernel.
Therefore, using if() replaces the BUG_ON.

Signed-off-by: Tina Zhang <tina.zhang@intel.com>
Link: https://lore.kernel.org/r/20230406065944.2773296-6-tina.zhang@intel.com


Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>