ESP32: Update Dockerfile for 4.2-r4

Author: rojer

tools/docker/esp32/Dockerfile-esp32-build

@@ -41,8 +41,8 @@ RUN git clone -j 8 --branch $DOCKER_TAG --depth 1 --recursive --shallow-submodul
 RUN cd /opt/Espressif/esp-idf && git tag v$DOCKER_TAG
 ENV IDF_PATH=/opt/Espressif/esp-idf
 
-ADD lwip_dns.patch /opt/Espressif/esp-idf/components/lwip/lwip
-RUN cd /opt/Espressif/esp-idf/components/lwip/lwip && patch -p 1 < lwip_dns.patch
+# Apply submodule patches.
+RUN cd $IDF_PATH && ./patch_submodules.sh
 
 # Pre-build configuration tools
 RUN cd $IDF_PATH/tools/kconfig && make conf-idf