powerpc/pseries/iommu: create DDW for devices with DMA mask less than 64-bits

powerpc/pseries/iommu: create DDW for devices with DMA mask less than 64-bits

Starting with PAPR level 2.13, platform supports placing PHB in limited
address mode. Devices that support DMA masks less that 64-bit but greater
than 32-bits are placed in limited address mode. In this mode, the
starting DMA address returned by the DDW is 4GB.

When the device driver calls dma_supported, with mask less then 64-bit, the
PowerPC IOMMU driver places PHB in the Limited Addressing Mode before
creating DDW.

Signed-off-by: Gaurav Batra <gbatra@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250108164814.73250-1-gbatra@linux.ibm.com