cr50: Use distinct configuration option for SPI Slave support

SPI slave and master interfaces require very different code to
support, they should have separate configuration options.

Host command code printouts should use their own console channel.

Using SPS to designate SPI Slave interface is not universally
acceptable, a bug has been opened to discuss the alternatives and
clean up the code.

BRANCH=none
BUG=chromium:512613
TEST=make buildall -j

Change-Id: I6683286a221c4689ecc247fdfe8ebca529f3f458
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/286469
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
7 files changed