iommu/exynos: fix device leak on of_xlate()

iommu/exynos: fix device leak on of_xlate()

Make sure to drop the reference taken to the iommu platform device when
looking up its driver data during of_xlate().

Note that commit 1a26044954a6 ("iommu/exynos: add missing put_device()
call in exynos_iommu_of_xlate()") fixed the leak in a couple of error
paths, but the reference is still leaking on success.

Fixes: aa759fd376fb ("iommu/exynos: Add callback for initializing devices from device tree")
Cc: stable@vger.kernel.org	# 4.2: 1a26044954a6
Cc: Yu Kuai <yukuai3@huawei.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>