vfio/container: pass MemoryRegion to DMA operations

vfio/container: pass MemoryRegion to DMA operations

Pass through the MemoryRegion to DMA operation handlers of vfio
containers. The vfio-user container will need this later, to translate
the vaddr into an offset for the dma map vfio-user message; CPR will
also will need this.

Originally-by: John Johnson <john.g.johnson@oracle.com>
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: John Levon <john.levon@nutanix.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Steve Sistare <steven.sistare@oracle.com>
Link: https://lore.kernel.org/qemu-devel/20250521215534.2688540-1-john.levon@nutanix.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>