platform/chrome: kunit: Avoid -Wflex-array-member-not-at-end

-Wflex-array-member-not-at-end was introduced in GCC-14, and we are
getting ready to enable it, globally.

Move the conflicting declaration to the end of the structure. Notice
that `struct cros_ec_command` is a flexible structure --a structure
that contains a flexible-array member.

Fix the following warning:

drivers/platform/chrome/cros_ec_proto_test_util.h:16:32: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

Signed-off-by: Gustavo A. R. Silva <[email protected]>
Link: https://lore.kernel.org/r/aBp7mZ8kj9w4CKkl@kspp
Signed-off-by: Tzung-Bi Shih <[email protected]>

Author: GustavoARSilva

drivers/platform/chrome/cros_ec_proto_test_util.h

@@ -13,14 +13,17 @@ struct ec_xfer_mock {
 	struct kunit *test;
 
 	/* input */
-	struct cros_ec_command msg;
 	void *i_data;
 
 	/* output */
 	int ret;
 	int result;
 	void *o_data;
 	u32 o_data_len;
+
+	/* input */
+	/* Must be last -ends in a flexible-array member. */
+	struct cros_ec_command msg;
 };
 
 extern int cros_kunit_ec_xfer_mock_default_result;