iommu/vt-d: Fix misplaced domain_attached assignment

iommu/vt-d: Fix misplaced domain_attached assignment

Commit fb5873b779dd ("iommu/vt-d: Restore context entry setup order
for aliased devices") was incorrectly backported: the domain_attached
assignment was mistakenly placed in device_set_dirty_tracking()
instead of original identity_domain_attach_dev().

Fix this by moving the assignment to the correct function as in the
original commit.

Fixes: fb5873b779dd ("iommu/vt-d: Restore context entry setup order for aliased devices")
Closes: https://lore.kernel.org/linux-iommu/721D44AF820A4FEB+722679cb-2226-4287-8835-9251ad69a1ac@bbaa.fun/
Cc: stable@vger.kernel.org
Reported-by: Ban ZuoXiang <bbaa@bbaa.fun>
Signed-off-by: Ban ZuoXiang <bbaa@bbaa.fun>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>