chore(lifecycle): Make it more explicit where core1_mutex needs to be locked

All current callers handle this correctly but the assumption that
core1_mutex is locked while calling do_load(), load_async(), or
load_sync() should not be implicit.  Make it more explicit by adding
mutex assertions in all three functions.

epicardium/modules/lifecycle.c

@@ -91,6 +91,9 @@ static int do_load(struct load_info *info)
 	struct l0dable_info l0dable;
 	int res;
 
+	/* Callers of do_load() must first lock the core1_mutex. */
+	mutex_assert_locked(&core1_mutex);
+
 	if (*info->name == '\0') {
 		LOG_INFO("lifecycle", "Loading Python interpreter ...");
 	} else {
@@ -159,6 +162,9 @@ out_free_api:
  */
 static int load_sync(char *name, bool reset)
 {
+	/* Callers of load_sync() must first lock the core1_mutex. */
+	mutex_assert_locked(&core1_mutex);
+
 	int ret = load_stat(name);
 	if (ret < 0) {
 		return ret;
@@ -181,6 +187,9 @@ static int load_sync(char *name, bool reset)
  */
 static int load_async(char *name, bool reset)
 {
+	/* Callers of load_async() must first lock the core1_mutex. */
+	mutex_assert_locked(&core1_mutex);
+
 	int ret = load_stat(name);
 	if (ret < 0) {
 		return ret;