platform/chrome: cros_ec_proto: Add version for ec_command

Add a version parameter to cros_ec_command() for callers that may want
to specify which version of the host command they would like to use.

Signed-off-by: Prashant Malani <pmalani@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Link: https://lore.kernel.org/r/20210930022403.3358070-5-pmalani@chromium.org