libnvdimm: Remove prototypes for nonexistent functions

These functions don't exist, so remove the prototypes for them.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
Reviewed-by: Frederic Barrat <fbarrat@linux.ibm.com>
Link: https://lore.kernel.org/r/20191025044721.16617-3-alastair@au1.ibm.com


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