ide-cd: remove ide_cd_init_rq

ide_cd_init_rq is not used by ide-cd_ioctl any more. Only
cdrom_queue_request_sense use it. This converts
cdrom_queue_request_sense to use blk_rq_init directly and removes
ide_cd_init_rq.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Borislav Petkov <petkovbb@gmail.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>