fs: btrfs: Use btrfs_readlink() to implement __btrfs_readlink()

The existing __btrfs_readlink() can be easily re-implemented using the
extent buffer based btrfs_readlink().

This is the first step to re-implement U-Boot's btrfs code.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Marek BehĂșn <marek.behun@nic.cz>
2 files changed