iommu/sun50i: fix device leak on of_xlate()

iommu/sun50i: fix device leak on of_xlate()

commit f916109bf53864605d10bf6f4215afa023a80406 upstream.

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

Fixes: 4100b8c229b3 ("iommu: Add Allwinner H6 IOMMU driver")
Cc: stable@vger.kernel.org	# 5.8
Cc: Maxime Ripard <mripard@kernel.org>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>