ch: remove debug noise in ch_do_scsi

The midlayer logging already prints the cdb details if the logging
level is high enough, no need to duplicate this in the ch driver.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Bottomley <JBottomley@Parallels.com>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>