FLAG to disable still requires RGB fields

[smckenna3]

If disabling the subsystem, should RGB fields be required? It was an easy work around. Just adding it for a future fix.

FLAGS: -x, --disable disable the RGB subsystem altogether

---

root@pc:~/msi-rgb/target/release# ./msi-rgb -x error: The following required arguments were not provided: <RED> <GREEN> <BLUE>

USAGE: msi-rgb <RED> <GREEN> <BLUE> --base-port <BASEPORT> --blink <BLINK> --disable --duration <STEPDURATION>

For more information try --help