platform/chrome: cros_ec: Add VDM attention headers

Incorporate updates to the EC headers to support the retrieval of VDM
Attention messages from port partners. These headers are already present
in the ChromeOS EC codebase. [1]

[1] https://source.chromium.org/chromium/chromiumos/platform/ec/+/main:include/ec_commands.h

Signed-off-by: Prashant Malani <pmalani@chromium.org>
[pmalani: Removed extra tab in header #define]
Reviewed-by: Benson Leung <bleung@chromium.org>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://lore.kernel.org/r/20230126205620.3714994-1-pmalani@chromium.org