brcmfmac: Replace zero-length arrays with flexible-array members

There is a regular need in the kernel to provide a way to declare
having a dynamically sized set of trailing elements in a structure.
Kernel code should always use “flexible array members”[1] for these
cases. The older style of one-element or zero-length arrays should
no longer be used[2].

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/78
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220216194935.GA904103@embeddedor

drivers/net/wireless/broadcom/brcm80211/brcmfmac/fwil_types.h

@@ -1068,7 +1068,7 @@ struct brcmf_mkeep_alive_pkt_le {
 	__le32  period_msec;
 	__le16  len_bytes;
 	u8   keep_alive_id;
-	u8   data[0];
+	u8   data[];
 } __packed;
 
 #endif /* FWIL_TYPES_H_ */

drivers/net/wireless/broadcom/brcm80211/brcmfmac/xtlv.h

@@ -15,7 +15,7 @@
 struct brcmf_xtlv {
 	u16 id;
 	u16 len;
-	u8 data[0];
+	u8 data[];
 };
 
 enum brcmf_xtlv_option {