NFSv4: remove CONFIG_NFS_V4 from nfs_read_data

Cleanup nfs_read_data. We also won't use CONFIG_NFS_V4_1 for additional
NFSv4.1 fields in subsequent patches.
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

include/linux/nfs_xdr.h

@@ -1016,9 +1016,7 @@ struct nfs_read_data {
 	unsigned int		npages;	/* Max length of pagevec */
 	struct nfs_readargs args;
 	struct nfs_readres  res;
-#ifdef CONFIG_NFS_V4
 	unsigned long		timestamp;	/* For lease renewal */
-#endif
 	struct page		*page_array[NFS_PAGEVEC_SIZE];
 };