Remove lots of micropython-specific remnants

Makefile

@@ -43,7 +43,7 @@ fix-isort: devdeps
 
 clean: clean-build-log
 	@echo "===> Cleaning build artifacts"
-	@rm -rf .submodules .circuitpy-deps .micropython-deps .devdeps build
+	@rm -rf .submodules .circuitpy-deps .devdeps build
 
 clean-build-log:
 	@echo "===> Clearing previous .build.log"
@@ -65,29 +65,7 @@ test: lint
 	@rsync -ah vendor/ build/
 	@touch .submodules
 
-.micropython-deps: .submodules
-	@echo "===> Building micropython/mpy-cross"
-	@echo "===> Building micropython/mpy-cross" >> .build.log
-	@pipenv run $(MAKE) -C build/micropython/mpy-cross 2>&1 >> .build.log
-	@touch .micropython-deps
-
 submodules: .submodules
-micropython-deps: .micropython-deps
-
-build/micropython/ports/unix/micropython: micropython-deps build/micropython/ports/unix/modules/.kmk_frozen
-	@echo "===> Building MicroPython for Unix"
-	@echo "===> Building MicroPython for Unix" >> .build.log
-	@pipenv run $(MAKE) -j4 -C build/micropython/ports/unix 2>&1 >> .build.log
-
-micropython-build-unix: build/micropython/ports/unix/micropython
-
-build/micropython/ports/unix/modules/.kmk_frozen: upy-freeze.txt submodules.toml
-	@echo "===> Preparing vendored dependencies for bundling into MicroPython for Unix"
-	@echo "===> Preparing vendored dependencies for bundling into MicroPython for Unix" >> .build.log
-	@rm -rf build/micropython/ports/unix/modules/*
-	@cat upy-freeze.txt | egrep -v '(^#|^\s*$|^\s*\t*#)' | grep MICROPY | cut -d'|' -f2- | \
-		xargs -I '{}' rsync -ah {} build/micropython/ports/unix/modules/
-	@touch $@
 
 reset-bootloader:
 	@echo "===> Rebooting your board to bootloader (safe to ignore file not found errors)"