sw64: iommu: fix iommu-flush ops to support multi-device passthrough

Sunway inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I73KII



--------------------------------

Current iommu-flush ops cannot handle the rare case which integrates
several groups of devices into 1 domain. Unluckily, QEMU can meet
this situation in some circumstances.

We fix the flush ops by flushing all devices in the domain's device
list, which makes iommu capable of mapping multiple devices correctly.

Signed-off-by: Xu Yiwei <xuyiwei@wxiat.com>
Reviewed-by: He Sheng <hesheng@wxiat.com>
Signed-off-by: Gu Zitao <guzitao@wxiat.com>