alsa_sound: remove redundant assignments of voiceVolume

This if/else pair is overriden immediately afterwards by the
assignment of voiceVolume.  The Bluetooth case is handled by the
subsequent check for (bluetooth+vgs) in which case voiceVolume
is set to max.

Change-Id: I616887690e2c59a7ad4c7fb3ef5cb8e22a42a565