mtd-utils: Instead of doing preprocessor magic, just output off_t as long long

mtd-utils: Instead of doing preprocessor magic, just output off_t as long long

Fix warnings abot PRIdoff_t in libmtd.c, in mtd_read (and mtd_write):

In file included from ../git/lib/libmtd.c:40:0:
../git/lib/libmtd.c: In function 'mtd_read':
../git/include/common.h:110:18: warning: format '%ld' expects argument of
 type 'long int', but argument 5 has type 'off_t {aka long long int}'
 [-Wformat=]

../git/include/common.h:120:2: note: in expansion of macro 'errmsg'
  errmsg(fmt, ##__VA_ARGS__);                                         \
  ^~~~~~
../git/lib/libmtd.c:1082:10: note: in expansion of macro 'sys_errmsg'
   return sys_errmsg("cannot seek mtd%d to offset %"PRIdoff_t,
          ^~~~~~~~~~

/usr/lib/klibc/include/inttypes.h:28:17: note: format string is defined here
 #define PRId32 "d"

Signed-off-by: Thorsten Glaser <tg@mirbsd.org>
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>