nfsd4: simplify references to nfsd4 lease time

Instead of accessing the lease time directly, some users call
nfs4_lease_time(), and some a macro, NFSD_LEASE_TIME, defined as
nfs4_lease_time().  Neither layer of indirection serves any purpose.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 4bc22c7..ed12ad4 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -455,7 +455,7 @@
 
 static int max_cb_time(void)
 {
-	return max(NFSD_LEASE_TIME/10, (time_t)1) * HZ;
+	return max(nfsd4_lease/10, (time_t)1) * HZ;
 }
 
 /* Reference counting, callback cleanup, etc., all look racy as heck.