scsi: dpt_i2o: remove redundant null check on array device

The null check on pHba->channel[chan].device is redundant because
device is an array and hence can never be null. Remove the check.

Detected by CoverityScan, CID#115362 ("Array compared against 0")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>