iommu/mediatek-v1: Add error handle for mtk_iommu_probe

In the original code, we lack the error handle. This patch adds them.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Link: https://lore.kernel.org/r/20210412064843.11614-2-yong.wu@mediatek.com


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