platform/chrome: add PD_EVENT_INIT bit definition

platform/chrome: add PD_EVENT_INIT bit definition

Update cros_ec_commands.h to include a definition for PD_EVENT_INIT.
On platforms supporting UCSI, this host event type is sent when the PPM
initializes.

Signed-off-by: Jameson Thies <jthies@google.com>
Reviewed-by: Benson Leung <bleung@chromium.org>
Acked-by: Tzung-Bi Shih <tzungbi@kernel.org>
Reviewed-by: Łukasz Bartosik <ukaszb@chromium.org>
Link: https://lore.kernel.org/r/20250204024600.4138776-2-jthies@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>