zephyr: Use MP_REGISTER_ROOT_POINTER().

This uses MP_REGISTER_ROOT_POINTER() to register port-specific root
pointers for the zephyr port.

Signed-off-by: David Lechner <david@pybricks.com>

ports/zephyr/machine_pin.c

@@ -322,4 +322,7 @@ STATIC const mp_irq_methods_t machine_pin_irq_methods = {
     .info = machine_pin_irq_info,
 };
 
+/* Linked list of pin irq objects */
+MP_REGISTER_ROOT_POINTER(void *machine_pin_irq_list);
+
 #endif // MICROPY_PY_MACHINE

ports/zephyr/modbluetooth_zephyr.c

@@ -418,4 +418,6 @@ int mp_bluetooth_gap_peripheral_connect_cancel(void) {
 
 #endif // MICROPY_PY_BLUETOOTH_ENABLE_CENTRAL_MODE
 
+MP_REGISTER_ROOT_POINTER(struct _mp_bluetooth_zephyr_root_pointers_t *bluetooth_zephyr_root_pointers);
+
 #endif // MICROPY_PY_BLUETOOTH

ports/zephyr/mpconfigport.h

@@ -133,10 +133,6 @@ typedef long mp_off_t;
 
 #define MP_STATE_PORT MP_STATE_VM
 
-#define MICROPY_PORT_ROOT_POINTERS \
-    void *machine_pin_irq_list; /* Linked list of pin irq objects */ \
-    struct _mp_bluetooth_zephyr_root_pointers_t *bluetooth_zephyr_root_pointers;
-
 // extra built in names to add to the global namespace
 #define MICROPY_PORT_BUILTINS \
     { MP_ROM_QSTR(MP_QSTR_open), MP_ROM_PTR(&mp_builtin_open_obj) },