filesystems: add missing nlink wrappers

Replace direct i_nlink updates with the respective updater function
(inc_nlink, drop_nlink, clear_nlink, inode_dec_link_count).

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
diff --git a/fs/cifs/link.c b/fs/cifs/link.c
index 8693b5d..6b0e064 100644
--- a/fs/cifs/link.c
+++ b/fs/cifs/link.c
@@ -433,7 +433,7 @@
 	if (old_file->d_inode) {
 		cifsInode = CIFS_I(old_file->d_inode);
 		if (rc == 0) {
-			old_file->d_inode->i_nlink++;
+			inc_nlink(old_file->d_inode);
 /* BB should we make this contingent on superblock flag NOATIME? */
 /*			old_file->d_inode->i_ctime = CURRENT_TIME;*/
 			/* parent dir timestamps will update from srv