libnvdimm: Fix ACPI_NFIT in BLK_DEV_PMEM help

The ACPI_NFIT config option is described incorrectly as the
inverse NFIT_ACPI, which doesn't exist, so update the help
to the actual config option.

Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
Link: https://lore.kernel.org/r/20240212123716.795996-1-pbrobinson@gmail.com


Signed-off-by: Dave Jiang <dave.jiang@intel.com>