iommu/rockchip: Allocate per-device data sensibly

Now that DT-based probing is finally happening in the right order again,
it reveals an issue in Rockchip's of_xlate, which can now be called
during registration, but is using the global dma_dev which is only
assigned later. However, this makes little sense when we're already
looking up the correct IOMMU device, who should logically be the owner
of the devm allocation anyway.

Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Fixes: bcb81ac6 ("iommu: Get DT/ACPI parsing into the proper probe path")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Quentin Schulz <quentin.schulz@cherry.de>
Tested-by: Dang Huynh <danct12@riseup.net>
Reviewed-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
Tested-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
Link: https://lore.kernel.org/r/771e91cf16b3048e93f657153b76905665878fa2.1741886382.git.robin.murphy@arm.com


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