[SCSI] scsi_dh_emc: request flag cleanup

blk_get_request sets the cmd_flags, so we should not and do not
need to set them. If we did set them to a different value then
it can cause a oops in the elevator code.

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