[SCSI] initio: bugfix for accessors patch

patch: [SCSI] initio: convert to use the data buffer accessors had a
small but fatal bug in that it didn't increment the pointer into the
initio scatterlist descriptors as it looped over the block generated
ones. Fixed here.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>