drm/exynos: use DRM_DEV_ERROR to print out error message

This patch just cleans up the use of error log macro, which changes
the log macro to DRM_DEV_ERROR.

Signed-off-by: Inki Dae <inki.dae@samsung.com>
diff --git a/drivers/gpu/drm/exynos/exynos_drm_plane.c b/drivers/gpu/drm/exynos/exynos_drm_plane.c
index df0508e..6328565 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_plane.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_plane.c
@@ -181,6 +181,7 @@
 			      struct exynos_drm_plane_state *state)
 {
 	struct drm_framebuffer *fb = state->base.fb;
+	struct drm_device *dev = fb->dev;
 
 	switch (fb->modifier) {
 	case DRM_FORMAT_MOD_SAMSUNG_64_32_TILE:
@@ -192,7 +193,7 @@
 		break;
 
 	default:
-		DRM_ERROR("unsupported pixel format modifier");
+		DRM_DEV_ERROR(dev->dev, "unsupported pixel format modifier");
 		return -ENOTSUPP;
 	}
 
@@ -310,7 +311,7 @@
 				       config->num_pixel_formats,
 				       NULL, config->type, NULL);
 	if (err) {
-		DRM_ERROR("failed to initialize plane\n");
+		DRM_DEV_ERROR(dev->dev, "failed to initialize plane\n");
 		return err;
 	}