ASoC: msm: Route VoLTE call to primary mi2s

Update the VoLTE_Tx Mixer control to handle
PRI_MI2S_TX_VoLTE and add the route from PRI_MI2S_TX
to VoLTE_Tx Mixer to support VoLTE call over
primary mi2s.

Change-Id: I59157f536d2b5da227868eb61ba7bf7fa9bf90cc
Signed-off-by: Helen Zeng <xiaoyunz@codeaurora.org>