msm: avs: Remove vestigial software based AVS

Older targets like 8x50 had the first version of Apdaptive Voltage
Scaling done in software. This feature was never enabled and supported.
Remove the code and the associated config items.

Change-Id: If3bdab7d0bdb5d51e099f7c37f56592826edc102
Signed-off-by: Praveen Chidambaram <pchidamb@codeaurora.org>