libnvdimm: introduce 'flags' attribute for DIMM 'lock' and 'alias' status

Given that we now how have two mechanisms for a DIMM to indicate that it
is locked:

    * NVDIMM_FAMILY_INTEL 'get_config_size' _DSM command

    * ACPI 6.2 Label Storage Read / Write commands

...export the generic libnvdimm DIMM status in a new 'flags' attribute.

This attribute can also reflect the 'alias' state which indicates
whether the nvdimm core is enforcing labels for aliased-region-capacity
that the given dimm is an interleave-set member.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>