iommu/mediatek-v1: Just rename mtk_iommu to mtk_iommu_v1

No functional change. Just rename this for readable. Differentiate this
from mtk_iommu.c

Signed-off-by: Yong Wu <[email protected]>
Reviewed-by: AngeloGioacchino Del Regno <[email protected]>
Reviewed-by: Matthias Brugger <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Joerg Roedel <[email protected]>

Author: YongWu-HF