Let through upto the largest command of 260 defined by the scsi standard.
iscsi core supports this already. Now that the scsi-ml supports it we can
start using large commands.

[jejb:rejections fixed up]
Signed-off-by: NBoaz Harrosh <bharrosh@panasas.com>
Acked-by: NMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>