Fix Possible Deadlock with getFeatureState

Use the ImsFeature lock for concurrency in MmTelFeature
instead of declaring its own lock.

Also, fixed up some other concurrency code.

Bug: 110507525
Test: Manual, Telephony Unit Tests
CRs-Fixed: 2280795
Change-Id: I5a7ef1beca619873a7c228bed0e1b82843d4de63
(cherry picked from commit 8f074959)