add option to pass symbol defines to ci build.py

add build.args option for hil json
add MAX3421_HOST=1 for metro m4 express

hw/bsp/samd5x_e5x/boards/metro_m4_express/board.cmake

@@ -3,9 +3,6 @@ set(SAM_FAMILY samd51)
 set(JLINK_DEVICE ATSAMD51J19)
 set(LD_FILE_GNU ${CMAKE_CURRENT_LIST_DIR}/${BOARD}.ld)
 
-# force max3421e for testing with hardware-in-the-loop
-set(MAX3421_HOST 1)
-
 function(update_board TARGET)
   target_compile_definitions(${TARGET} PUBLIC
     __SAMD51J19A__