include: Add snapshot of header files for wcd spi and dsp manager

This is a snapshot of wcd-spi.h and wcd-dsp-mgr.h for wcd spi and
dsp manager as of msm-4.14 commit <af1e41>(Add header files for
wcd spi and dsp manager).

Change-Id: Iaffcecb946ac5e60ab99c7b7a7d5c06259ab7344
Signed-off-by: Meng Wang <mwang@codeaurora.org>