nfit: Clarify memory device state flags strings

ACPI 6.0 NFIT Memory Device State Flags in Table 5-129 defines
NVDIMM status as follows.  These bits indicate multiple info,
such as failures, pending event, and capability.

  Bit [0] set to 1 to indicate that the previous SAVE to the
  Memory Device failed.
  Bit [1] set to 1 to indicate that the last RESTORE from the
  Memory Device failed.
  Bit [2] set to 1 to indicate that platform flush of data to
  Memory Device failed. As a result, the restored data content
  may be inconsistent even if SAVE and RESTORE do not indicate
  failure.
  Bit [3] set to 1 to indicate that the Memory Device is observed
  to be not armed prior to OSPM hand off. A Memory Device is
  considered armed if it is able to accept persistent writes.
  Bit [4] set to 1 to indicate that the Memory Device observed
  SMART and health events prior to OSPM handoff.

/sys/bus/nd/devices/nmemX/nfit/flags shows this flags info.
The output strings associated with the bits are "save", "restore",
"smart", etc., which can be confusing as they may be interpreted
as positive status, i.e. save succeeded.

Change also the dev_info() message in acpi_nfit_register_dimms()
to be consistent with the sysfs flags strings.

Reported-by: Robert Elliott <elliott@hp.com>
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
[ross: rename 'not_arm' to 'not_armed']
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
[djbw: defer adding bit5, HEALTH_ENABLED, for now]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>