py: Fix dummy definition of BEGIN/END_ATOMIC_SECTION.
diff --git a/py/mpconfig.h b/py/mpconfig.h
index 618b8fd..4efe21d 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -431,10 +431,10 @@
 
 // On embedded platforms, these will typically enable/disable irqs.
 #ifndef MICROPY_BEGIN_ATOMIC_SECTION
-#define MICROPY_BEGIN_ATOMIC_SECTION()
+#define MICROPY_BEGIN_ATOMIC_SECTION() (0)
 #endif
 #ifndef MICROPY_END_ATOMIC_SECTION
-#define MICROPY_END_ATOMIC_SECTION()
+#define MICROPY_END_ATOMIC_SECTION(state) (void)(state)
 #endif
 
 // Allow to override static modifier for global objects, e.g. to use with