Use correct token for drm image format
diff --git a/compositor.c b/compositor.c
index 8a2b956..9ca06b0 100644
--- a/compositor.c
+++ b/compositor.c
@@ -648,7 +648,7 @@
 		EGL_WIDTH,		0,
 		EGL_HEIGHT,		0,
 		EGL_IMAGE_STRIDE_MESA,	0,
-		EGL_IMAGE_FORMAT_MESA,	EGL_FORMAT_RGBA_8888_KHR,
+		EGL_IMAGE_FORMAT_MESA,	EGL_IMAGE_FORMAT_ARGB8888_MESA,
 		EGL_NONE
 	};