iommu/mediatek: Add tlb_lock in tlb_flush_all

The tlb_flush_all touches the registers controlling tlb operations.
Protect it with the tlb_lock spinlock.
This also require the range_sync func to release that spinlock before
calling tlb_flush_all.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
[refactor commit log]
Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20211208120744.2415-5-dafna.hirschfeld@collabora.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>