NFS: Fix more sparse warnings

 - fs/nfs/nfs4xdr.c:2499:42: warning: incorrect type in argument 2
   (different signedness)
 - fs/nfs/nfs4xdr.c:2658:49: warning: incorrect type in argument 4
   (different explicit signedness)
 - fs/nfs/nfs4xdr.c:2683:50: warning: incorrect type in argument 4
   (different explicit signedness)
 - fs/nfs/nfs4xdr.c:3063:68: warning: incorrect type in argument 4
   (different explicit signedness)
 - fs/nfs/nfs4xdr.c:3065:68: warning: incorrect type in argument 4
   (different explicit signedness)

 - fs/nfs/callback_xdr.c:138:31: warning: incorrect type in argument 2
   (different signedness)

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/callback.h b/fs/nfs/callback.h
index db3d791..c2bb14e 100644
--- a/fs/nfs/callback.h
+++ b/fs/nfs/callback.h
@@ -24,7 +24,7 @@
 };
 
 struct cb_compound_hdr_arg {
-	int taglen;
+	unsigned int taglen;
 	const char *tag;
 	unsigned int callback_ident;
 	unsigned nops;
@@ -32,7 +32,7 @@
 
 struct cb_compound_hdr_res {
 	__be32 *status;
-	int taglen;
+	unsigned int taglen;
 	const char *tag;
 	__be32 *nops;
 };