Revert "CI: make clean for ESP32, just for safety"

This reverts commit 70a1e1a.

Author: jonnor

.github/workflows/build.yaml

@@ -118,9 +118,7 @@ jobs:
         make -C mpy-cross
     - name: Setup submodules esp32
       working-directory: micropython/ports/esp32
-      run: |
-        source ../../esp-idf/export.sh && make submodules
-        make clean
+      run: source ../../esp-idf/export.sh && make submodules
     - name: Build custom firmware with extmod, ESP32
       run: |
         source micropython/esp-idf/export.sh && pip install -r requirements.txt