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/dat.c b/fs/nilfs2/dat.c
index 59e5fe7..fcc2f86 100644
--- a/fs/nilfs2/dat.c
+++ b/fs/nilfs2/dat.c
@@ -54,7 +54,7 @@
 static void nilfs_dat_commit_entry(struct inode *dat,
 				   struct nilfs_palloc_req *req)
 {
-	nilfs_mdt_mark_buffer_dirty(req->pr_entry_bh);
+	mark_buffer_dirty(req->pr_entry_bh);
 	nilfs_mdt_mark_dirty(dat);
 	brelse(req->pr_entry_bh);
 }
@@ -361,7 +361,7 @@
 	entry->de_blocknr = cpu_to_le64(blocknr);
 	kunmap_atomic(kaddr, KM_USER0);
 
-	nilfs_mdt_mark_buffer_dirty(entry_bh);
+	mark_buffer_dirty(entry_bh);
 	nilfs_mdt_mark_dirty(dat);
 
 	brelse(entry_bh);