iommu/mediatek: Fix leaked of_node references

iommu/mediatek: Fix leaked of_node references

The call to of_parse_phandle returns a node pointer with refcount
incremented thus it must be explicitly decremented after the last
usage.

581 static int mtk_iommu_probe(struct platform_device *pdev)
582 {
    ...
626         for (i = 0; i < larb_nr; i++) {
627                 struct device_node *larbnode;
    ...
631                 larbnode = of_parse_phandle(...);
632                 if (!larbnode)
633                         return -EINVAL;
634
635                 if (!of_device_is_available(larbnode))
636                         continue;             ---> leaked here
637
    ...
643                 if (!plarbdev)
644                         return -EPROBE_DEFER; ---> leaked here
    ...
647                 component_match_add_release(dev, &match, release_of,
648                                             compare_of, larbnode);
                                   ---> release_of will call of_node_put
649         }
    ...
650

Detected by coccinelle with the following warnings:
./drivers/iommu/mtk_iommu.c:644:3-9: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 631, but without a corresponding object release within this function.

Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: iommu@lists.linux-foundation.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mediatek@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Matthias Brugger <mbrugger@suse.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>