f2fs: introduce get_dirty_dents for readability

The get_dirty_dents gives us the number of dirty dentry pages.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index 60920ac..ef90af8 100644
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -268,7 +268,7 @@
 			inode->i_ino == F2FS_META_INO(sbi))
 		goto no_delete;
 
-	f2fs_bug_on(atomic_read(&F2FS_I(inode)->dirty_dents));
+	f2fs_bug_on(get_dirty_dents(inode));
 	remove_dirty_dir_inode(inode);
 
 	if (inode->i_nlink || is_bad_inode(inode))