Fix small bug in ESP32 mkimage.sh when using the help option

Change the script to exit after printing the help, instead of erroneously reporting that the image
was successfully created.

Signed-off-by: Winford <[email protected]>

Author: UncleGrumpy

src/platforms/esp32/tools/mkimage.sh.in

@@ -25,6 +25,11 @@ escript "@CMAKE_BINARY_DIR@/mkimage.erl" \
     --out "@CMAKE_BINARY_DIR@/atomvm-@[email protected]" \
     "$@"
 
+if (test ${@} = "--help"); then
+    echo ""
+    exit 0;
+fi
+
 echo "============================================="
 
 echo ""