ide-cd: move lba_to_msf() and msf_to_lba() to <linux/cdrom.h>

* Move lba_to_msf() and msf_to_lba() to <linux/cdrom.h>
  (use 'u8' type instead of 'byte' while at it).

* Remove msf_to_lba() copy from drivers/cdrom/cdrom.c.

Acked-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>