HAL: Fix vts-on-gsi test failure

audio_extn_utils_is_vendor_enhanced_fwk is judge by "ro.vendor.qti.va_aosp.support" prop which is in system image.
With GSI, the prop "ro.vendor.qti.va_aosp.support" become false and policy can support AUDIO_CHANNEL_OUT_MONO.
VTS will test AUDIO_CHANNEL_OUT_MONO but HAL will set to AUDIO_CHANNEL_OUT_STEREO which
result in mismatch in channel config resulting vts failure.

This change is to remove check for stereo channel support for voip over audio path.
Updated the change to avoid mismatch channel config.

Change-Id: Id3d34504fbd46e2820c72bc612096dae6edb8d78