iommu/mediatek: Validate number of phandles associated with "mediatek,larbs"

iommu/mediatek: Validate number of phandles associated with "mediatek,larbs"

Fix the smatch warnings:
drivers/iommu/mtk_iommu.c:878 mtk_iommu_mm_dts_parse() error: uninitialized
symbol 'larbnode'.

If someone abuse the dtsi node(Don't follow the definition of dt-binding),
for example "mediatek,larbs" is provided as boolean property, "larb_nr"
will be zero and cause abnormal.

To fix this problem and improve the code safety, add some checking
for the invalid input from dtsi, e.g. checking the larb_nr/larbid valid
range, and avoid "mediatek,larb-id" property conflicts in the smi-larb
nodes.

Fixes: d2e9a1102cfc ("iommu/mediatek: Contain MM IOMMU flow with the MM TYPE")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/r/20221018024258.19073-5-yong.wu@mediatek.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>