Ignore additional encrypt change events when link is auth & encrypted

Bug: 243105146
Test: Tested initial setup sequence between wearable device and Phone,
made sure wearable device is ignoring the additional encrypt change
events when the link is already authenticated and encrypted.
Processing additional enc change event was causing pairing failure issues.

Change-Id: I4c85ef176296b31e094b08705ab6293aae11f927
(cherry picked from commit 63be13b923a6aa3819660488e69e3ef11d2f0c0a)