ACPI: NFIT: Move bus_dsm_mask out of generic nvdimm_bus_descriptor

DSMs are strictly an ACPI mechanism, evict the bus_dsm_mask concept from
the generic 'struct nvdimm_bus_descriptor' object.

As a side effect the test facility ->bus_nfit_cmd_force_en is no longer
necessary. The test infrastructure can communicate that information
directly in ->bus_dsm_mask.

Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>