firewire: ohci: Replace zero-length array with flexible-array

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://github.com/KSPP/linux/issues/21

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

drivers/firewire/core-transaction.c

@@ -620,7 +620,7 @@ struct fw_request {
 	u32 request_header[4];
 	int ack;
 	u32 length;
-	u32 data[0];
+	u32 data[];
 };
 
 static void free_response_callback(struct fw_packet *packet,