udf: Push i_data_sem locking into udf_expand_file_adinicb()

The checks we do in udf_setsize() and udf_file_write_iter() are safe to
do only with i_rwsem locked as it stabilizes both file type and file
size. Hence we don't need to lock i_data_sem before we enter
udf_expand_file_adinicb() which simplifies the locking somewhat.

Signed-off-by: Jan Kara <jack@suse.cz>