kconfig: gconf: replace GtkHPaned and GtkVPaned with GtkPaned
GtkHPaned and GtkVPaned are deprecated with GTK 3.2. [1] [2]
Use GtkPaned instead.
[1]: https://gitlab.gnome.org/GNOME/gtk/-/blob/3.2.0/gtk/gtkhpaned.c#L44
[2]: https://gitlab.gnome.org/GNOME/gtk/-/blob/3.2.0/gtk/gtkvpaned.c#L44
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>