[SCSI] add DID_REQUEUE string to scsi_show_result host table

I was working on patches which add new transport error values, when I
noticed that DID_REQUEUE was not in the hostbyte_table. I do not think
there is any way to hit the code path where scsi_show_result is called
and where you return DID_REQUEUE, because DID_REQUEUE causes scsi-ml to
always requeue the command. However, for completeness and because I want
to one day send a patch that tries to add new host bytes values, I am
sending this patch.

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