py/runtime: Allow initialising sys.path/argv with defaults.

If MICROPY_PY_SYS_PATH_ARGV_DEFAULTS is enabled (which it is by default)
then sys.path and sys.argv will be initialised and populated with default
values.  This keeps all bare-metal ports aligned.

Signed-off-by: Damien George <damien@micropython.org>

ports/zephyr/main.c

@@ -139,9 +139,6 @@ soft_reset:
     gc_init(heap, heap + sizeof(heap));
     #endif
     mp_init();
-    mp_obj_list_init(mp_sys_path, 0);
-    mp_obj_list_append(mp_sys_path, MP_OBJ_NEW_QSTR(MP_QSTR_)); // current dir (or base dir of the script)
-    mp_obj_list_init(mp_sys_argv, 0);
 
     #ifdef CONFIG_USB
     usb_enable(NULL);