libata: Implement control mode page to select sense format

Implement MODE SELECT for the control mode page to allow the OS
to switch to descriptor sense.

tj: Dropped s/sb/cmd->sense_buffer/ in ata_gen_ata_sense().  Added
    @dev description to ata_msense_ctl_mode().

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Tejun Heo <tj@kernel.org>