lib: vsprintf.c: replace NUM_TYPE with s64/u64 types

This fixes warnings when compiling with ELDK-5.2.1 for MIPS64:

vsprintf.c: In function 'put_dec':
vsprintf.c:258:9: warning: comparison of distinct pointer types lacks a cast [enabled by default]
vsprintf.c:258:3: warning: passing argument 1 of '__div64_32' from incompatible pointer type [enabled by default]
include/div64.h:22:17: note: expected 'uint64_t *' but argument is of type 'long long unsigned int *'

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>