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/affs/namei.c b/fs/affs/namei.c
index e3e9efc..780a11d 100644
--- a/fs/affs/namei.c
+++ b/fs/affs/namei.c
@@ -277,7 +277,7 @@
 	inode->i_mapping->a_ops = (AFFS_SB(sb)->s_flags & SF_OFS) ? &affs_aops_ofs : &affs_aops;
 	error = affs_add_entry(dir, inode, dentry, ST_FILE);
 	if (error) {
-		inode->i_nlink = 0;
+		clear_nlink(inode);
 		iput(inode);
 		return error;
 	}
@@ -305,7 +305,7 @@
 
 	error = affs_add_entry(dir, inode, dentry, ST_USERDIR);
 	if (error) {
-		inode->i_nlink = 0;
+		clear_nlink(inode);
 		mark_inode_dirty(inode);
 		iput(inode);
 		return error;
@@ -392,7 +392,7 @@
 	return 0;
 
 err:
-	inode->i_nlink = 0;
+	clear_nlink(inode);
 	mark_inode_dirty(inode);
 	iput(inode);
 	return error;