scsi: Revert "scsi: hisi_sas: Drain bcast events in hisi_sas_rescan_topology()"

scsi: Revert "scsi: hisi_sas: Drain bcast events in hisi_sas_rescan_topology()"

This reverts commit 11ff0c98fca35df16c84d4eee52008faecaf10a6.

Draining or flushing events in hisi_sas_rescan_topology() can hang the
driver, typically with phy up or phy down events being processed,
i.e. sas_porte_bytes_dmaed() or sas_phye_loss_of_signal().

Signed-off-by: Jie Zhan <zhanjie9@hisilicon.com>
Link: https://lore.kernel.org/r/20221118083714.4034612-2-zhanjie9@hisilicon.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>