ide-cd: remove struct ide_cd_{config,state}_flags

* Remove unused ->{writing,reserved} fields from struct ide_cd_config_flags.

* Move ->max_speed from struct ide_cd_config_flags to struct cdrom_info.

* Move ->current_speed from struct ide_cd_state_flags to struct cdrom_info.

* Add defines for config and state flags.

* Add 'unsigned int cd_flags' to struct cdrom_info and use ->cd_flags
  instead of ->{config,state}_flags.

* Remove no longer needed struct ide_cd_{config,state}_flags.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>