refactoring machine.c, two files per device

.github/workflows/build.yml

@@ -20,7 +20,7 @@ jobs:
           apt install make gcc sdcc xxd python-is-python3 libjson-c-dev zlib1g-dev -y
       - name: Run the host-side unit tests
         run: make -C test
-      - name: Check if machine.c can be compiled for all machines
+      - name: Check that every machine definition can be compiled
         run: make machine_check
       - name: Make project (4x2/RTL8372)
         run: make CI=1 MACHINE="KP_9000_6XHML_X2"