fix rp2040 examples build from local tinyusb tree

hw/bsp/rp2040/family.cmake

@@ -17,7 +17,7 @@ if (NOT TARGET _rp2040_family_inclusion_marker)
 	include(${CMAKE_CURRENT_LIST_DIR}/boards/${BOARD}/board.cmake)
 
 	# TOP is absolute path to root directory of TinyUSB git repo
-	set(TOP "../../..")
+	set(TOP "${CMAKE_CURRENT_LIST_DIR}/../../..")
 	get_filename_component(TOP "${TOP}" REALPATH)
 
 	if (NOT PICO_TINYUSB_PATH)