iommu/vt-d: Remove unnecessary domain_context_mapped()

The device_domain_info::domain accurately records the domain attached to
the device. It is unnecessary to check whether the context is present in
the attach_dev path. Remove it to make the code neat.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20221118132451.114406-7-baolu.lu@linux.intel.com


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