sw64: iommu: fix 32-bit devices dma ops

Sunway inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I56OSP



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dma_mask is not sufficient to determine whether the device is 32-bit
or not, while coherent_dma_mask is required as well. The addressing
capability of a device depends on the minimum of them.

Because 32-bit devices with sunway_dma_ops have to be set to
IOMMU_DOMAIN_DMA, which may raise DMA using address allocated by BIOS
and lead to iommu exception. So we change dma ops to arch-specific
direct dma_ops for 32-bit devices.

Signed-off-by: Zheng Chongzhen <zhengchongzhen@wxiat.com>

Signed-off-by: Gu Zitao <guzitao@wxiat.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>