esp32: disable MSC interface

The MSC interface is unlikely to be useful, and probably would do more
harm than good if someone tries to upload the .fw image.

esp32/Makefile

@@ -17,6 +17,9 @@ ARDUINO_OPTS  = -b $(BOARD) \
 		--build-cache-path ../cache \
 		--build-property 'build.flash_size=4MB' \
 		--build-property 'build.defines=-DBOARD_HAS_PSRAM' \
+		--build-property 'build.cdc_on_boot=1' \
+		--build-property 'build.msc_on_boot=0' \
+		--build-property 'build.dfu_on_boot=1' \
 		--build-property 'build.partitions=min_spiffs'
 
 all: $(TARGET)