py/mpprint: Remove unreachable check for neg return of mp_format_float.

py/mpprint.c

@@ -354,9 +354,6 @@ int mp_print_float(const mp_print_t *print, mp_float_t f, char fmt, int flags, c
     }
 
     int len = mp_format_float(f, buf, sizeof(buf), fmt, prec, sign);
-    if (len < 0) {
-        len = 0;
-    }
 
     char *s = buf;