[Tizen] fix tts issue in text controller

[Tizen] fix tts issue in text controller

When text is entered in IME,
InsertText() can be called several times at the same time. (preedit + commit)

Sometimes the tts player does not respond at this time.
Actually.. tts player works again after checking the connection after a while.
But this wastes the user's time and makes them feel bad.
So I try to avoid this case by reducing unnecessary tts play calls.

Change-Id: I702ca0ed354bcd3c249b6ccc012d4aa23a6b4e08
Signed-off-by: Bowon Ryu <bowon.ryu@samsung.com>