Revert "add header with rgb struct definition"

This reverts commit f2c5e3ae9d.
Algernon pointed out that we can't depend on the ordering of the struct
at the Kaleidoscope level

src/cRGB.h

@@ -1,6 +0,0 @@
-#pragma once
-struct cRGB {
-    uint8_t b;
-    uint8_t g;
-    uint8_t r;
-};