util: remove unused definitions of RED, GREEN, and BLUE

These are unused since commit edcef53685 ("modetest: Add test
pattern support for missing RGB formats").

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
v2:
  - Add Reviewed-by.

tests/util/pattern.c

@@ -766,11 +766,6 @@ static void fill_smpte(const struct util_format_info *info, void *planes[3],
 	}
 }
 
-/* swap these for big endian.. */
-#define RED   2
-#define GREEN 1
-#define BLUE  0
-
 static void make_pwetty(void *data, unsigned int width, unsigned int height,
 			unsigned int stride, uint32_t format)
 {