ASoC: msm: qdsp6v2: fix slow_talk not disabled issue

If slow talk is disabled from the settings menu after voice
call is ended, the command is not sent to dsp since the voc state
is not in VOC_RUN and on next call CVS still has slow talk property
enabled. Fix by disabling slow talk when voice call is ended.

CRs-Fixed: 607911
Change-Id: I2c312e41b14fca021f8d41380c3b5c8493710255
Signed-off-by: Shiv Maliyappanahalli <smaliyap@codeaurora.org>