codal_port/modspeech: include mphal.h for the simulator

MICROPY_BEGIN_ATOMIC_SECTION/MICROPY_END_ATOMIC_SECTION are only defined
in modspeech because of mpconfigport.h (indirectly). Include mphal.h so
that the defaults are defined if the port does not define them (as in
the sim case).

Author: microbit-matt-hillsdon

src/codal_port/modspeech.c

@@ -28,6 +28,7 @@
 #include <stdio.h>
 #include <string.h>
 
+#include "py/mphal.h"
 #include "py/obj.h"
 #include "py/objtuple.h"
 #include "py/objstr.h"