[SCSI] scsi_dh_emc: fix mode select request setup

This patch fixes the request setup code for mode selects. I got the fixes from
Hannes Reinecke while trying to hunt down some problems and merged it
into one patch. I am sending it because Hannes is busy with other things.

The patch fixes:
- setting of the length for mode selects.
- setting of the data direction for mode select 10.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>