iommu/mediatek: Move geometry.aperture updating into domain_finalise

Move the domain geometry.aperture updating into domain_finalise.
This is a preparing patch for updating the domain region. We know the
detailed iova region in the attach_device.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Link: https://lore.kernel.org/r/20210111111914.22211-26-yong.wu@mediatek.com
Signed-off-by: Will Deacon <will@kernel.org>