Allow encryption request to proceed in unrelated states

Device security state is shared for both transports. Encryption request is saved if security
state is not idle.
This means that security state for a transport can block encryption request the encryption
request for another transport. Saved encryption requests are revived for just updating the
requester of encryption change status when encryption change is event is generated. Thus the
saved encryption requests are never acted upon.
For, example if LE encryption is requested while the BR/EDR link is disconnecting, the LE
encryption request is blocked and never acted upon.

Test: m com.android.btservices
Bug: 294886212
Change-Id: I7d29f6575d0b5ed3578051d800976c5f3149e552