ASoC: wcd934x: update keeper enable for soundwire functionality

Keeper enable bit is used to reduce the current leakage
from soundwire master. Enable this bit before starting
audio use-case through soundwire and disable once
use-case is completed.

Change-Id: If2dc9e7fd9a2710391d02c0e52a291b3cffc63b6
Signed-off-by: Phani Kumar Uppalapati <phaniu@codeaurora.org>