scsi: aacraid: Do not wait for outstanding write commands on synchronize_cache

There is no need to wait for outstanding write commands on synchronize
cache; the block layer is responsible for I/O scheduling, no need to
out-guess it in the driver layer.

Link: https://lore.kernel.org/r/20200228075318.91255-5-hare@suse.de


Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Balsundar P <balsundar.b@microchip.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>