devlink: fix format string warning for 32bit targets

devlink: fix format string warning for 32bit targets

32bit targets define uint64_t as long long unsigned. This leads to the
following build warning:

devlink.c: In function ‘pr_out_u64’:
devlink.c:1729:11: warning: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 4 has type ‘uint64_t {aka long long unsigned int}’ [-Wformat=]
    pr_out("%s %lu", name, val);
           ^
devlink.c:59:21: note: in definition of macro ‘pr_out’
   fprintf(stdout, ##args);   \
                     ^~~~

Use uint64_t specific conversion specifiers in the format string to fix
that.

Cc: Aya Levin <ayal@mellanox.com>
Cc: Moshe Shemesh <moshe@mellanox.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>