g: sps: at initialization wait for the master to finish SPI cycle
g: sps: at initialization wait for the master to finish SPI cycle

TPM reset processing takes certain time, and conceivably the AP could
start SPI transactions before TPM reset is finished. If the SPS
interface comes up while the CS line is active, the H1 controller
considers this a start of the SPI cycle, even though it is not - the
AP has already transferred the header and is waiting for the flow
control.

Let's not complete SPS interface initialization while the CS line is
kept active.

BRANCH=cr50
BUG=b:68012381
TEST=verified that the AP firmware test passes

Change-Id: I53cd49c6139f3c29c4b6d234c7ee4d527c8282f6
Signed-off-by: Vadim Bendebury <5515d6d2d0829cbe0dd0dcf2094aaded06d58514@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/754504
Reviewed-by: Randall Spangler <62698fdbb84d1779579ee80c3f39fac22017e5bc@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec