acpi/nfit, libnvdimm: Add support for issue secure erase DSM to Intel nvdimm

acpi/nfit, libnvdimm: Add support for issue secure erase DSM to Intel nvdimm

Add support to issue a secure erase DSM to the Intel nvdimm. The
required passphrase is acquired from an encrypted key in the kernel user
keyring. To trigger the action, "erase <keyid>" is written to the
"security" sysfs attribute.

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