NFSv4.1: Convert slotid from u8 to u32

It is perfectly legal to negotiate up to 2^32-1 slots in the protocol,
and with 10GigE, we are already seeing that 255 slots is far too limiting.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/callback.h b/fs/nfs/callback.h
index 197e0d3..a5527c9 100644
--- a/fs/nfs/callback.h
+++ b/fs/nfs/callback.h
@@ -38,7 +38,7 @@
 struct cb_process_state {
 	__be32			drc_status;
 	struct nfs_client	*clp;
-	int			slotid;
+	u32			slotid;
 	struct net		*net;
 };