fix error handling for unsupported commands

- Respond with failure for unsupported task management commands
- Increase MaxRecvDataSegmentLength to 65536, to match FirstBurstLength

Signed-off-by: Utkarsh Mani Tripathi <utkarsh.tripathi@mayadata.io>

pkg/port/iscsit/iscsid.go

@@ -841,10 +841,8 @@ func (s *ISCSITargetDriver) iscsiExecTask(task *iscsiTask) error {
 			fallthrough
 		case ISCSI_TM_FUNC_TARGET_WARM_RESET, ISCSI_TM_FUNC_TARGET_COLD_RESET, ISCSI_TM_FUNC_TASK_REASSIGN:
 			task.result = ISCSI_TMF_RSP_NOT_SUPPORTED
-			return fmt.Errorf("The task function is not supported")
 		default:
 			task.result = ISCSI_TMF_RSP_REJECTED
-			return fmt.Errorf("Unknown task function")
 		}
 		// return response to initiator
 		return task.conn.buildRespPackage(OpSCSITaskResp, task)