py: Fix mp_obj_t -> mp_const_obj_t for mp_obj_int_get_checked()

Signed-off-by: Sven Wegener <sven.wegener@stealer.net>
diff --git a/py/objint.c b/py/objint.c
index 34447b3..3aaf510 100644
--- a/py/objint.c
+++ b/py/objint.c
@@ -258,7 +258,7 @@
     return MP_OBJ_SMALL_INT_VALUE(self_in);
 }
 
-machine_int_t mp_obj_int_get_checked(mp_obj_t self_in) {
+machine_int_t mp_obj_int_get_checked(mp_const_obj_t self_in) {
     return MP_OBJ_SMALL_INT_VALUE(self_in);
 }