affs: struct affs_data_head: Replace 1-element array with flexible array

Replace the deprecated[1] use of a 1-element array in
struct affs_data_head with a modern flexible array.

No binary differences are present after this conversion.

Link: https://github.com/KSPP/linux/issues/79 [1]
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Kees Cook <kees@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/affs/amigaffs.h

@@ -119,7 +119,7 @@ struct affs_data_head
 	__be32 size;
 	__be32 next;
 	__be32 checksum;
-	u8 data[1];	/* depends on block size */
+	u8 data[];	/* depends on block size */
 };
 
 /* Permission bits */