drm/ast: AST2000 cannot be detected correctly

Type error and cause AST2000 cannot be detected correctly
Signed-off-by: NY.C. Chen <yc_chen@aspeedtech.com>
Reviewed-by: NEgbert Eich <eich@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/ast/ast_main.c

@@ -105,7 +105,7 @@ static int ast_detect_chip(struct drm_device *dev)
 			}
 			ast->vga2_clone = false;
 		} else {
-			ast->chip = 2000;
+			ast->chip = AST2000;
 			DRM_INFO("AST 2000 detected\n");
 		}
 	}