* tui/tui-regs.c (tui_show_register_group): Remove GDBARCH parameter;

	use frame architecture instead.  Replace current_gdbarch uses.
	(tui_show_registers): Update call.
	(tui_get_register): Remove GDBARCH parameter; use frame architecture
	instead.
	(tui_show_register_group): Update call.
	(tui_check_register_values): Likewise.
	(tui_register_format): Remove GDBARCH parameter; use frame
	architecture instead.  Replace current_gdbarch uses.
	(tui_get_register): Update call.