Provide a convenience wrapper for general purpose dataset
management commands. The previous wrapper for deallocate
was difficult to use correctly and only for deallocate.
Note that the name is "dataset_management" as opposed to
"data_set_management" to match the NVMe specification.
It's questionable whether "dataset" is valid English, but
it is best to match the specification.
Change-Id: Ifc03d66dbabeabe8146968cf8a09f7ac3446ad68
Signed-off-by: Ben Walker <benjamin.walker@intel.com>