Filesystems also have duplicate code to support ->get_link() on
encrypted symlinks.  Factor it out into a new function
fscrypt_get_symlink().  It takes in the contents of the encrypted
symlink on-disk and provides the target (decrypted or encoded) that
should be returned from ->get_link().
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>