scsi: libcxgbi: fix incorrect DDP resource cleanup

Before calling task_release_itt() task data is memset to zero because of
which DDP context information is lost resulting in incorrect DDP
resource cleanup, to fix this call task_release_itt() before memset.

Signed-off-by: Varun Prakash <varun@chelsio.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>