msm-pcm-lpa: 8960: Issue EOS to DSP after playback is complete

Issue an EOS command to ensure that dsp is completely flushed
before closing the stream. This command is only issued if the
the routing is still enabled.

Change-Id: Id36f2b1a2e5e3fef5dcde759277f3ca4417c17e7
CRs-Fixed: 331532
Signed-off-by: Tejas Shikhare <tshikhar@codeaurora.org>