Prevent state change even if no recognition result callback is registered

Prevent state change even if no recognition result callback is registered

Current code changes the state to ready when the result comes from the server without registered
recognition result callback. However, this behavior can make difference between client state and
real server state.

To handle this potential issue, this patch prevents the state change in this case. By this change,
client state is always matched with server state.

Change-Id: I4df2438fb09d00185318b487b8f233ba0918798b
Signed-off-by: Suyeon Hwang <stom.hwang@samsung.com>