audioflinger: Fix deletion of input buffer in EffectChain

mInBuffer, when it is owned by EffectChain, comes from
AudioFlinger::PlaybackThread::addEffectChain_l where it is
allocated using "new[]", and thus needs to be deleted
using "delete[]".

Change-Id: Ib16bab59f9e00627f8ef52f7232ebdd74a6c9a74
Test: make