uacce: misc fixes

driver inclusion
category: bugfix
bugzilla: NA
CVE: NA

1.add input para check of uacce_unregister api
2.change uacce_qfrt_str to internal interface, because it is used
  just in uacce.c

Signed-off-by: Yu'an Wang <wangyuan46@huawei.com>
Reviewed-by: Longfang Liu <liulongfang@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>