Unregister TIDL stub port when connection is closed

Unregister TIDL stub port when connection is closed

- Issue:
Connected event callback is invoked even though the connection is
closed.

- Solution:
Previous code does not invoke unregister method of TIDL stub, so the
connection callback still can be invoked even if the client
succeeds to deinitialize. And this is no intended behavior, so this
patch fixes this behaivor. Through this patch, widget module will
properly call unregister method. And also, widget module will check
first if the stub information is valid.

Change-Id: I1864824237218468b5341eb32c23c17e9f278651
Signed-off-by: Suyeon Hwang <stom.hwang@samsung.com>