staging: speakup: fix leaks of sysfs groups

speakup_kobj_init() and speakup_kobj_exit() didn't remove
i18n_attr_group and main_attr_group sysfs groups.

Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>