MAP: Only call failPendingMessages() when unlocked

Usecase:
1) Enable Direct boot mode in DUT.
2) Reboot DUT and connect to remote device in Locked state.
3) Disconnect from remote device(with failed pending messages).

Issue:
Exception while moving pending messages from outbox to failed.

Root Cause:
As database is not accessible in Direct Boot Mode, it results in
fatal exception while trying to move messages from outbox to failed
when remote disconnects and DUT is still not unlocked.

Fix:
Prevent failPendingMessages if device is not unlocked in Direct
Boot Mode.

Test: Checked if BT does not crash during remote disconnection in
direct boot mode

Bug: 38382980
Change-Id: I616ed3bfb2e390c420658b8927de547ad70d1bea