if of_find_device_by_node() succeed, exynos_iommu_of_xlate() doesn't have
a corresponding put_device(). Thus add put_device() to fix the exception
handling for this function implementation.

Fixes: aa759fd3 ("iommu/exynos: Add callback for initializing devices from device tree")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20200918011335.909141-1-yukuai3@huawei.comSigned-off-by: Joerg Roedel <jroedel@suse.de>