drm/exynos: vidi: fix build warning

encoder object isn't used anymore so remove it.

Signed-off-by: Inki Dae <inki.dae@samsung.com>
diff --git a/drivers/gpu/drm/exynos/exynos_drm_vidi.c b/drivers/gpu/drm/exynos/exynos_drm_vidi.c
index 9395e85..50faf91 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_vidi.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_vidi.c
@@ -630,7 +630,6 @@
 {
 	struct exynos_drm_manager *mgr = platform_get_drvdata(pdev);
 	struct vidi_context *ctx = mgr->ctx;
-	struct drm_encoder *encoder = ctx->encoder;
 
 	if (ctx->raw_edid != (struct edid *)fake_edid_info) {
 		kfree(ctx->raw_edid);