get rid of lkmc package, move userland and kernel-modules to top

Rationale: we already had a non buildroot build system,
maintaining both will be hard, and having short paths is more awesome.

userland/hello_cpp.cpp

@@ -0,0 +1,7 @@
+/* https://github.com/cirosantilli/linux-kernel-module-cheat#sanity-checks */
+
+#include <iostream>
+
+int main() {
+    std::cout << "hello cpp" << std::endl;
+}