kernel: dynamic: add missing assert argument

Add a missing assert argument, fixes:

zephyrproject/zephyr/kernel/dynamic.c: In function 'dyn_cb':
zephyrproject/zephyr/include/zephyr/sys/__assert.h:44:52: warning:
	format '%p' expects a matching 'void *' argument [-Wformat=]

That started to break the build since:

d7846de548 assert: check format arguments for correctness

Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>
diff --git a/kernel/dynamic.c b/kernel/dynamic.c
index 23e64e8..5215e83 100644
--- a/kernel/dynamic.c
+++ b/kernel/dynamic.c
@@ -112,7 +112,8 @@
 	struct dyn_cb_data *const data = (struct dyn_cb_data *)user_data;
 
 	if (data->stack == (k_thread_stack_t *)thread->stack_info.start) {
-		__ASSERT(data->tid == NULL, "stack %p is associated with more than one thread!");
+		__ASSERT(data->tid == NULL, "stack %p is associated with more than one thread!",
+			 (void *)thread->stack_info.start);
 		data->tid = (k_tid_t)thread;
 	}
 }