mesh: Move Device UUID log to bt_mesh_prov_enable()

In some cases the application might only initialize its UUID after
calling bt_mesh_init(), e.g. in the case of deriving the UUID from the
identity address. To avoid confusing logs, only print the UUID when
actually enabling one of the provisioing bearers.

nimble/host/mesh/src/mesh.c

@@ -15,6 +15,7 @@
 #include "syscfg/syscfg.h"
 #define BT_DBG_ENABLED (MYNEWT_VAL(BLE_MESH_DEBUG))
 #include "host/ble_hs_log.h"
+#include "host/ble_uuid.h"
 
 #include "adv.h"
 #include "prov.h"
@@ -137,6 +138,15 @@ int bt_mesh_prov_enable(bt_mesh_prov_bearer_t bearers)
 		return -EALREADY;
 	}
 
+	if (MYNEWT_VAL(BLE_MESH_DEBUG)) {
+		char uuid_buf[BLE_UUID_STR_LEN];
+		const struct bt_mesh_prov *prov = bt_mesh_prov_get();
+		ble_uuid_t *uuid = BLE_UUID128_DECLARE();
+
+		memcpy(BLE_UUID128(uuid)->value, prov->uuid, 16);
+		BT_INFO("Device UUID: %s", ble_uuid_to_str(uuid, uuid_buf));
+	}
+
 	if (IS_ENABLED(CONFIG_BT_MESH_PB_ADV) &&
 	    (bearers & BT_MESH_PROV_ADV)) {
 		/* Make sure we're scanning for provisioning inviations */