keys: encrypted-type: 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/21Signed-off-by: NGustavo A. R. Silva <gustavoars@kernel.org>

include/keys/encrypted-type.h

@@ -27,7 +27,7 @@ struct encrypted_key_payload {
 	unsigned short payload_datalen;		/* payload data length */
 	unsigned short encrypted_key_format;	/* encrypted key format */
 	u8 *decrypted_data;	/* decrypted data */
-	u8 payload_data[0];	/* payload data + datablob + hmac */
+	u8 payload_data[];	/* payload data + datablob + hmac */
 };
 
 extern struct key_type key_type_encrypted;