travis: Add BLE submodules to ESP32 IDF4 build.

.travis.yml

@@ -160,7 +160,7 @@ jobs:
         - make ${MAKEOPTS} -C ports/esp32 clean
         # IDF v4 build
         - git -C esp-idf checkout $(grep "ESPIDF_SUPHASH_V4 :=" ports/esp32/Makefile | cut -d " " -f 3)
-        - git -C esp-idf submodule update --init components/esp_wifi/lib_esp32 components/esptool_py/esptool components/lwip/lwip components/mbedtls/mbedtls
+        - git -C esp-idf submodule update --init components/bt/controller/lib components/bt/host/nimble/nimble components/esp_wifi/lib_esp32 components/esptool_py/esptool components/lwip/lwip components/mbedtls/mbedtls
         - make ${MAKEOPTS} -C ports/esp32
 
     # esp8266 port