udf: Parameterize output length in udf_put_filename

Make the desired output length a parameter rather than have it
hard-coded to UDF_NAME_LEN. Although all call sites still have
this length the same, this parameterization will make the function
more universal and also consistent with udf_get_filename.

Signed-off-by: Andrew Gabbasov <andrew_gabbasov@mentor.com>
Signed-off-by: Jan Kara <jack@suse.cz>