NFS: When displaying session slot numbers, use "%u" consistently

Clean up, since slot and sequence numbers are all unsigned anyway.

Among other things, squelch compiler warnings:

linux/fs/nfs/nfs4proc.c: In function ‘nfs4_setup_sequence’:
linux/fs/nfs/nfs4proc.c:703:2: warning: signed and unsigned type in
	conditional expression [-Wsign-compare]

and

linux/fs/nfs/nfs4session.c: In function ‘nfs4_alloc_slot’:
linux/fs/nfs/nfs4session.c:151:31: warning: signed and unsigned type in
	conditional expression [-Wsign-compare]

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 85b1906..05742b8 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -664,7 +664,7 @@
 
 	args->sa_slot = slot;
 
-	dprintk("<-- %s slotid=%d seqid=%d\n", __func__,
+	dprintk("<-- %s slotid=%u seqid=%u\n", __func__,
 			slot->slot_nr, slot->seq_nr);
 
 	res->sr_slot = slot;
@@ -704,9 +704,9 @@
 		goto out;
 	}
 
-	dprintk("--> %s clp %p session %p sr_slot %d\n",
+	dprintk("--> %s clp %p session %p sr_slot %u\n",
 		__func__, session->clp, session, res->sr_slot ?
-			res->sr_slot->slot_nr : -1);
+			res->sr_slot->slot_nr : NFS4_NO_SLOT);
 
 	ret = nfs41_setup_sequence(session, args, res, task);
 out: