bootloaders/riotboot_dfu: Use ztimer instead of ztimer

bootloaders/riotboot_dfu/Makefile

@@ -5,7 +5,8 @@ APPLICATION = riotboot_dfu
 USEMODULE += riotboot_usb_dfu
 
 # Use xtimer for scheduled reboot
-USEMODULE += xtimer
+USEMODULE += ztimer
+USEMODULE += ztimer_auto_init
 
 # USB device vendor and product ID
 # pid.codes test VID/PID, not globally unique

bootloaders/riotboot_dfu/main.c

@@ -26,6 +26,7 @@
 #include "panic.h"
 #include "riotboot/slot.h"
 #include "riotboot/usb_dfu.h"
+#include "ztimer.h"
 
 #include "bootloader_selection.h"
 
@@ -70,6 +71,9 @@ void kernel_init(void)
         riotboot_slot_jump(slot);
     }
 
+    /* Init ztimer before starting DFU mode */
+    ztimer_init();
+
     /* Nothing to boot, stay in DFU mode to flash a slot */
     riotboot_usb_dfu_init(1);
 }