nvdimm: constify device_type structures

Declare device_type structure as const as it is only stored in the
type field of a device structure. This field is of type const, so add
const to declaration of device_type structure.

File size before:
  text	   data	    bss	    dec	    hex	filename
  19278	   3199	     16	  22493	   57dd	nvdimm/namespace_devs.o

File size after:
  text	   data	    bss	    dec	    hex	filename
  19929	   3160	     16	  23105	   5a41	nvdimm/namespace_devs.o

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

path: root/ioexact.h

#ifndef IOEXACT_H
#define IOEXACT_H

#include <stdbool.h>

extern ssize_t read_exact(int fd, void *buf, size_t len, bool mayexit);
extern ssize_t write_exact(int fd, void *buf, size_t len, bool mayexit);

#endif /* IOEXACT_H */