soundwire: Add API to control slave device data path

Add soundwire API to control slave device data path
enable or disable. This gives slave device drivers
more flexibility for data path control during device
path enablement.

CRs-fixed: 996586
Change-Id: Ic0ab015098035418458a5ba7c2ffad9df20f933c
Signed-off-by: Phani Kumar Uppalapati <phaniu@codeaurora.org>