rog-control-center: Disable slint KMS backend

The slint KMS backend is meant to run an application without a display
server and with direct, exclusive display and input control, which is a
very specific use-case for e.g. embedded applications.

Disable the KMS backend and avoid a bunch of dependencies.

rog-control-center/Cargo.toml

@@ -51,7 +51,6 @@ default-features = false
 features = [
     "gettext",
     "compat-1-2",
-    "backend-linuxkms",
     "backend-winit-wayland",
     "renderer-winit-femtovg",
     # "renderer-skia-opengl",