ide: remove ide_init_drive_cmd

ide_init_drive_cmd just calls blk_rq_init. This converts the users of
ide_init_drive_cmd to use blk_rq_init directly and removes
ide_init_drive_cmd.

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>