fix dfu example build

examples/device/dfu/CMakeLists.txt

@@ -9,10 +9,9 @@ get_filename_component(TOP "${TOP}" REALPATH)
 # Check for -DFAMILY=
 if(FAMILY STREQUAL "rp2040")
   cmake_minimum_required(VERSION 3.12)
-  set(PICO_SDK_PATH ${TOP}/hw/mcu/raspberrypi/pico-sdk)
-  include(${PICO_SDK_PATH}/pico_sdk_init.cmake)
+
+  include(${TOP}/hw/bsp/${FAMILY}/pico_sdk_import.cmake)
   project(${PROJECT})
-  pico_sdk_init()
   add_executable(${PROJECT})
 
   include(${TOP}/hw/bsp/${FAMILY}/family.cmake)
@@ -33,9 +32,6 @@ if(FAMILY STREQUAL "rp2040")
     CFG_TUSB_OS=OPT_OS_PICO
   )
 
-  target_link_libraries(${PROJECT} pico_stdlib pico_fix_rp2040_usb_device_enumeration)
-  pico_add_extra_outputs(${PROJECT})
-
 else()
-  message(FATAL_ERROR "Invalid FAMILY specified")
+  message(FATAL_ERROR "Invalid FAMILY specified: ${FAMILY}")
 endif()