Bluetooth: btintel: Replace zero-length array with flexible-array member

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/v5.9/process/deprecated.html#zero-length-and-one-element-arraysSigned-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

drivers/bluetooth/btintel.h

@@ -47,7 +47,7 @@ enum {
 struct intel_tlv {
 	u8 type;
 	u8 len;
-	u8 val[0];
+	u8 val[];
 } __packed;
 
 struct intel_version_tlv {