iommu/mediatek: Just move code position in hw_init

No functional change too, prepare for mt8195 IOMMU support bank functions.
Some global control settings are in bank0 while the other banks have
their bank independent setting. Here only move the global control
settings and the independent registers together.

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/20220503071427.2285-26-yong.wu@mediatek.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>