Add timeout to lock in MtpServer configure

In situations where MtpServer is in a bad state, this will prevent
the configure call from blocking indefinitely, which will prevent
a few visible problems and allow the state to recover on the next
config change.

Bug: 34873000
Test: Connect to AA test sled
Change-Id: I5daf9cfcec69c967bde6bf3f6fd90e1c434e18bb