vfio: Make vfio_container_query_dirty_bitmap() static

vfio: Make vfio_container_query_dirty_bitmap() static

vfio_container_query_dirty_bitmap() is only used in "container-base.c".
Also, rename to vfio_container_iommu_query_dirty_bitmap() to reflect it
is using the VFIO IOMMU backend device ->query_dirty_bitmap() handler.

Reviewed-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: John Levon <john.levon@nutanix.com>
Reviewed-by: Avihai Horon <avihaih@nvidia.com>
Link: https://lore.kernel.org/qemu-devel/20250326075122.1299361-29-clg@redhat.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>