iommu/vt-d: Remove a useless BUG_ON(dev->is_virtfn)

When dmar_alloc_pci_notify_info() is being invoked, the invoker has
ensured the dev->is_virtfn is false. So, remove the useless BUG_ON in
dmar_alloc_pci_notify_info().

Signed-off-by: Tina Zhang <tina.zhang@intel.com>
Link: https://lore.kernel.org/r/20230406065944.2773296-7-tina.zhang@intel.com


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