-Wflex-array-member-not-at-end was introduced in GCC-14, and we are
getting ready to enable it, globally.
Use the `DEFINE_RAW_FLEX()` helper for on-stack definitions of
a flexible structure where the size of the flexible-array member
is known at compile-time, and refactor the rest of the code,
accordingly.
So, with these changes, fix the following warning:
drivers/watchdog/cros_ec_wdt.c:29:40: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
Reviewed-by: Tzung-Bi Shih <tzungbi@xxxxxxxxxx>
Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>