carl9170: Avoid -Wflex-array-member-not-at-end warning

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

Move the conflicting declaration (which happens to be in a union, so
we're moving the entire union) to the end of the corresponding
structure. Notice that `struct carl9170_rsp` is a flexible structure,
this is a structure that contains a flexible-array member.

With these changes fix the following warning:

drivers/net/wireless/ath/carl9170/carl9170.h:382:9: 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 <gustavoars@kernel.org>
Acked-by: Christian Lamparter <chunkeey@gmail.com>
Link: https://patch.msgid.link/aR1yxjmzb2DM2-Uq@kspp
Signed-off-by: Kees Cook <kees@kernel.org>

Author: GustavoARSilva

drivers/net/wireless/ath/carl9170/carl9170.h

@@ -375,11 +375,6 @@ struct ar9170 {
 	u8 *readbuf;
 	spinlock_t cmd_lock;
 	struct completion cmd_wait;
-	union {
-		__le32 cmd_buf[PAYLOAD_MAX + 1];
-		struct carl9170_cmd cmd;
-		struct carl9170_rsp rsp;
-	};
 
 	/* statistics */
 	unsigned int tx_dropped;
@@ -463,6 +458,13 @@ struct ar9170 {
 		unsigned int cache_idx;
 	} rng;
 #endif /* CONFIG_CARL9170_HWRNG */
+
+	/* Must be last as it ends in a flexible-array member. */
+	union {
+		__le32 cmd_buf[PAYLOAD_MAX + 1];
+		struct carl9170_cmd cmd;
+		struct carl9170_rsp rsp;
+	};
 };
 
 enum carl9170_ps_off_override_reasons {