py/mpprint: Fix "%x" vs "%X" regression introduced in previous commit.
@@ -511,7 +511,7 @@ int mp_vprintf(const mp_print_t *print, const char *fmt, va_list args) {
break;
case 'x':
case 'X': {
- char fmt_c = 'x' - *fmt + 'A';
+ char fmt_c = *fmt - 'X' + 'A';
mp_uint_t val;
if (long_arg) {
val = va_arg(args, unsigned long int);
