Kconfig: add Kconfig support for DFU

sys/usb/usbus/Kconfig

@@ -43,5 +43,6 @@ config USBUS_EP0_SIZE_64
 endchoice
 
 rsource "cdc/Kconfig"
+rsource "dfu/Kconfig"
 
 endif # KCONFIG_USEMODULE_USBUS

sys/usb/usbus/dfu/Kconfig

@@ -0,0 +1,35 @@
+
+# Copyright (c) 2020 Mesotic SAS
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+#
+menuconfig KCONFIG_USEMODULE_USBUS_DFU
+    bool "Configure USBUS DFU"
+    depends on USEMODULE_USBUS_DFU
+    help
+        Configure the USBUS DFU module via Kconfig.
+
+if KCONFIG_USEMODULE_USBUS_DFU
+
+config USB_DFU_DETACH_TIMEOUT_MS
+    int
+    range 0 65535
+    prompt "DFU detach timeout (ms)"
+    default 255
+    help
+        Indicates the detach timeout USB device should advertise to
+        the host USB. Host USB should abort the pending operation if
+        device doesn't detach after this timeout.
+
+config CUSTOM_RIOTBOOT_DFU_ADDR
+    bool "Use custom DFU magic address"
+    help
+        Say n to use the default address, which is the last in RAM.
+
+config RIOTBOOT_DFU_ADDR
+    int "DFU magic address"
+    depends on CUSTOM_RIOTBOOT_DFU_ADDR
+
+endif # KCONFIG_USEMODULE_USBUS_DFU