nilfs2: use mark_buffer_dirty to mark btnode or meta data dirty

This replaces nilfs_mdt_mark_buffer_dirty and nilfs_btnode_mark_dirty
macros with mark_buffer_dirty and gets rid of nilfs_mark_buffer_dirty,
an own mark buffer dirty function.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/fs/nilfs2/ifile.c b/fs/nilfs2/ifile.c
index bfc73d3..684d763 100644
--- a/fs/nilfs2/ifile.c
+++ b/fs/nilfs2/ifile.c
@@ -80,7 +80,7 @@
 		return ret;
 	}
 	nilfs_palloc_commit_alloc_entry(ifile, &req);
-	nilfs_mdt_mark_buffer_dirty(req.pr_entry_bh);
+	mark_buffer_dirty(req.pr_entry_bh);
 	nilfs_mdt_mark_dirty(ifile);
 	*out_ino = (ino_t)req.pr_entry_nr;
 	*out_bh = req.pr_entry_bh;
@@ -128,7 +128,7 @@
 	raw_inode->i_flags = 0;
 	kunmap_atomic(kaddr, KM_USER0);
 
-	nilfs_mdt_mark_buffer_dirty(req.pr_entry_bh);
+	mark_buffer_dirty(req.pr_entry_bh);
 	brelse(req.pr_entry_bh);
 
 	nilfs_palloc_commit_free_entry(ifile, &req);