ASoC: msm: Add support for VoLTE feature on mdm9x15

Add changes for VoLTE feature in machine driver
for mdm9x15. Along with this change VoLTE changes for cpu,
routing, platform and proxy voice driver changes are
required for VoLTE to work.

Change-Id: Ia0a3f84f2b2c4094facaa819e628d9778b664580
Signed-off-by: Venkat Sudhir <vsudhir@codeaurora.org>