ASoC: msm: Add volume control to set volume on platform driver

The existing interface uses combinatin of k-control in routing driver
and a global structure defined in the platform driver to send volume
to DSP. Add support to use the k-control defined in platform driver
for volume control. The platform driver can add the k-control by the
volume API snd_pcm_add_volume_ctls().

CRs-Fixed: 499201
Change-Id: I3c037595c0ae6e0ed1ea13e1270a220b551ea8af
Signed-off-by: Subhash Chandra Bose Naripeddy <snariped@codeaurora.org>