iommu/mediatek: Add mt6779 basic support

1. Start from mt6779, INVLDT_SEL move to offset=0x2c, so we add
   REG_MMU_INV_SEL_GEN2 definition and mt6779 uses it.
2. Add mt6779_data to support mm_iommu HW init.

Signed-off-by: Chao Hao <chao.hao@mediatek.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Yong Wu <yong.wu@mediatek.com>
Link: https://lore.kernel.org/r/20200703044127.27438-11-chao.hao@mediatek.com


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