nfs: replace nfs_add_stats with nfs_inc_stats when add one

Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index d489ff3..af3af68 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -575,7 +575,7 @@
 	int ret;
 
 	nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGE);
-	nfs_add_stats(inode, NFSIOS_WRITEPAGES, 1);
+	nfs_inc_stats(inode, NFSIOS_WRITEPAGES);
 
 	nfs_pageio_cond_complete(pgio, page_file_index(page));
 	ret = nfs_page_async_flush(pgio, page, wbc->sync_mode == WB_SYNC_NONE);