drm/exynos: fix no hdmi output

The hdmi outputs black screen only even though under the hood Xorg and
framebuffer console are fine : devices found and initialized, but
not a pixel out.

Commit 93bca243ec96 ("drm/exynos: remove struct exynos_drm_manager")
changed the call order of mixer_initialize with regards to
exynos_drm_crtc_create.

This changes breaks hdmi out on Odroid U2 (linux-next with added
Marek Szyprowski v4 hdmi patchset from linux-samsung-soc ML).

Restore the previous call ordering get hdmi to ouput proper pixels:
ie call mixer_initialize first then exynos_drm_crtc_create.

Fixes: 93bca243ec96 ("drm/exynos: remove struct exynos_drm_manager")
Signed-off-by: Alban Browaeys <[e-mail]>
Signed-off-by: Inki Dae <[e-mail]>

drivers/gpu/drm/exynos/exynos_mixer.c

···
 	struct drm_device *drm_dev = data;
 	int ret;
 
+	ret = mixer_initialize(ctx, drm_dev);
+	if (ret)
+		return ret;
+
 	ctx->crtc = exynos_drm_crtc_create(drm_dev, ctx->pipe,
 				     EXYNOS_DISPLAY_TYPE_HDMI,
 				     &mixer_crtc_ops, ctx);
 	if (IS_ERR(ctx->crtc)) {
+		mixer_ctx_remove(ctx);
 		ret = PTR_ERR(ctx->crtc);
 		goto free_ctx;
 	}
-
-	ret = mixer_initialize(ctx, drm_dev);
-	if (ret)
-		goto free_ctx;
 
 	return 0;