audioflinger: Fix the LPA-AudioEffects dead lock issue.

- Issue:Deadlock occurs when the LPA clips are subjected to
  rapid next from BT device and simultaneously on/off the
  audio effects.
- Rootcause:some times flinger thread processing
  LPAPlayer/directtrack next deadlocks with the thread
  working on effect configuration as both of them
  contend for the audioflinger::mlock and effectmodule::mlock.
- Fix1:AudioFlinger::deleteEffectSession() not to acquire
  audioflinger:mLock  instead take the mLPAEffectChain.mlock.
- Fix2:ThreadBase::effectConfigChanged() not to acquire
  audioflinger::mlock.

Change-Id: I056c8297802f81644fa1371836db42bdbd3825fd
CRs-Fixed: 477511