platform/chrome: cros_ec_proto: check `msg->result` in getting cmd mask

cros_ec_get_host_command_version_mask() should check if EC wasn't happy
by checking `msg->result`.

Use cros_ec_map_error() and return the error code if any.

Reviewed-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://lore.kernel.org/r/20220609084957.3684698-17-tzungbi@kernel.org