Assign handle after tts_create() success

Assign handle after tts_create() success

Previous code assigns the new handle before all process of tts_create() is finished. So, if
some process failed, client can get garbage point as a output parameter. It might occur wrong
behavior. And also, wrong pointer is passed into tts_config module because output parameter is
directly used.

This patch makes temporary handle for processing tts_create(), and passes this handle after all
process of tts_create() is success. And also by this change, tts config module gets right pointer
of handle.

Change-Id: I78f32da442b28cf996f357f2b9875a9d4c5e8ec7
Signed-off-by: Suyeon Hwang <stom.hwang@samsung.com>