CEC: Wait for send-event after cec writes in ectool
CEC: Wait for send-event after cec writes in ectool

For factory testing purposes, make the cecwrite
return-value depend on whether it got an ACK from the sink.

Signed-off-by: Stefan Adolfsson <e50dd6be847b40d13b2945548d6ccde363cae74b@chromium.org>

BUG=b:76467407
BRANCH=none
TEST=Using EC firmware with CEC support, ectool cecwrite with
and without sink
CQ-DEPEND=CL:1030215

Change-Id: I681243f74e4745796ac8d50e60dc0f7f9c087335
Reviewed-on: https://chromium-review.googlesource.com/1030216
Commit-Ready: Stefan Adolfsson <e50dd6be847b40d13b2945548d6ccde363cae74b@chromium.org>
Tested-by: Stefan Adolfsson <e50dd6be847b40d13b2945548d6ccde363cae74b@chromium.org>
Reviewed-by: Randall Spangler <62698fdbb84d1779579ee80c3f39fac22017e5bc@chromium.org>
Reviewed-by: Daisuke Nojiri <fd5f93af191bf7e8f73ea71cc3c0f66b41b1dd49@chromium.org>

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