[Tizen] Fix the Keyboard disappeared issue in TextField

[Tizen] Fix the Keyboard disappeared issue in TextField

- This patch can be reverted to the next DALi version.

- On the TV emulator, when the users press the OK key
  in DALi TextField application, the virtual keyboard(IME) disappeared.
- Recently, new Key mapping table in TV was created
  : DALI_KEY_OK enum value == "Return"
- In TextField, if the keyPressedName is "Return" && KeyEvent::Up,
  then called ClearKeyInputFocus().

Change-Id: I17b45b2de3a3ece524e19207a37a07262f37c7b9
Signed-off-by: Seoyeon Kim <seoyeon2.kim@samsung.com>