ndctl: release v56

This release incorporates the capabilities of the 4.10 kernel. Major
highlights include the new 'daxctl' utility and its 'list' command, as
well as several usability tweaks and cleanups to 'ndctl
create-namespace' and 'ndctl list'.

Commands:
    ndctl list: add support for filtering by namespace mode
    daxctl list: generically list device-dax instances in a platform
    ndctl create-namespace: reconcile namespace size against interleave-width

Tests:
    test: sanity check the unit test kernel modules befor running tests
    device-dax: extend it to test 4K and 1G alignments in addition to 2M
    multi-pmem: check namespace deletion cleanup

Apis:
    ndctl_{pfn,dax}_has_align: detect kernels that lack the align attribute
    ndctl_{set,get}_private_data: attach private data to a library context
    daxctl_region_get_size: retrieve the total dax region size
    daxctl_region_get_align: retrieve the physical alignment of the region
    daxctl_region_get_{first,next}: enable listing of device-dax regions