snd_soc_msm: Fix default value for TTY mode

Fix the default value for the TTY mode mixer control. This
will avoid setting invalid mode to ADSP and this is needed
to disable the TTY mode properly.

Change-Id: I743d0a0ae20f1b3b78d198e7917744f2948f95ab
CRs-Fixed: 697463
Merge "snd_soc_msm: Fix default value for TTY mode"