ASoC: msm: q6dspv2: use wrapper to access parent widget for kcontrol

Use snd_soc_dapm_kcontrol_widget() wrapper available ALSA core
to access the parent widget for a Kcontrol.

Change-Id: Ia4afed558cc64bb9a81da2b441183bb1b94a6461
Signed-off-by: Banajit Goswami <bgoswami@codeaurora.org>