[FT32] Implement pointer to address conversion method.

[FT32] Implement pointer to address conversion method.

FT32 is a Harvard architecture with two address spaces -- RAM and flash.
The patch properly implements the pointer to address conversion method.
There are some other small fixes to handle address spaces.

gdb/
	* ft32-tdep.c (ft32_register_type): Return gdbarch_tdep
	(gdbarch)->pc_type instead of builtin_func_ptr.
	(ft32_pointer_to_address): New function.
	(ft32_address_class_type_flags): New function.
	(ft32_address_class_type_flags_to_name): New function.
	(ft32_address_class_name_to_type_flags): New function.
	(ft32_gdbarch_init): Set tdep->pc_type.  Call
	set_gdbarch_pointer_to_address,
	set_gdbarch_address_class_type_flags
	set_gdbarch_address_class_name_to_type_flags,
	and set_gdbarch_address_class_type_flags_to_name.
	* ft32-tdep.h (struct gdbarch_tdep) <pc_type>: New field.