audioflinger: Fix pops in LPA while effects are applied

 -Issue: LPA playback while effect are applied, has pops/noise
  as below scenarios
  1) LPA Playback + taking snapshot with camera
  2) LPA Playback + changing media volume from settings app
  3) LPA plaback after non-LPA playback
 -Rootcause:Effects meant for LPA are getting applied in
  normal playback path
 -Fix: In threadloop of mixerthread if current effect
  chain is equal to LPAeffectchain, don't apply effects.

CRs-Fixed: 526799

Change-Id: Ic255ef2db81545abd119633e8fc6a7bae5d2f38c
audioflinger: Fix delay in enabling effect for LPA

 - Enable/disable of effects for LPA is taking time
 - Enable notification is not sent to effects thread till
   configure is called on each effect with isForLPA flag
   set to true, this happens only when applyEffcts is
   called in write of directoutput thread, so till that time
   effects are not applied and there is a delay in effects
   getting applied.
 - Insted of checking effcts LPA flag check the effectchain's
   LPA flag while sending notification to effects thread

Change-Id: I8d7559a60e5c6769d72022517daa05c84df54885
CRs-Fixed: 525510