ASoC: wcd934x: Enable smart boost on WCD9340 codec

During playback, enabling smart boost feature changes the threshold
of the playback signal based on the amplitude of the signal without
clipping the signal. Change enables smart boost on WCD9340 codec.

Change-Id: Ic4c5e3cc071898f376070b853112c5014d61272c
Signed-off-by: Sudheer Papothi <spapothi@codeaurora.org>