[libhandy] hdy-preferences-page: remove unused struct

[Alexander Mikhaylenko <alexm src gnome org>]

commit 6184749e0028f123f14e31a0a0fab8b6d941aa3b
Author: ZenWalker <scow riseup net>
Date:   Tue Jun 1 11:26:45 2021 +0200

    hdy-preferences-page: remove unused struct

 src/hdy-preferences-page.c | 6 ------
 1 file changed, 6 deletions(-)
---
diff --git a/src/hdy-preferences-page.c b/src/hdy-preferences-page.c
index 4d5ee3a1..f8fbdc6f 100644
--- a/src/hdy-preferences-page.c
+++ b/src/hdy-preferences-page.c
@@ -46,12 +46,6 @@ enum {
 
 static GParamSpec *props[LAST_PROP];
 
-typedef struct {
-  HdyPreferencesPage *preferences_page;
-  GtkCallback callback;
-  gpointer data;
-} CallbackData;
-
 static void
 hdy_preferences_page_get_property (GObject    *object,
                                    guint       prop_id,