firmware: disable internal PROGRAM pull-up

There is an external pull-up starting in Cynthion r0.6. The internal
pull-up could cause problems starting in Cynthion r0.7.

firmware/src/boards/luna_d11/usb_switch.c

@@ -43,6 +43,11 @@ void take_over_usb(void)
  */
 void switch_control_task(void)
 {
+#if ((_BOARD_REVISION_MAJOR_ == 0) && (_BOARD_REVISION_MINOR_ < 6))
+	gpio_set_pin_pull_mode(PROGRAM_BUTTON, GPIO_PULL_UP);
+#else
+	gpio_set_pin_pull_mode(PROGRAM_BUTTON, GPIO_PULL_OFF);
+#endif
 	gpio_set_pin_direction(PROGRAM_BUTTON, GPIO_DIRECTION_IN);
 	gpio_set_pin_direction(FPGA_INT, GPIO_DIRECTION_IN);
 	if ((gpio_get_pin_level(PROGRAM_BUTTON) == false) || (gpio_get_pin_level(FPGA_INT) == true)) {