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