lib: scsi: do not set IMMED bit of SYNCHRONIZE CACHE command

Current scsi backend implementation sets IMMED bit of SYNCHRONIZE CACHE
command. Then zbc_flush() call does not wait for cache synchronization
completion on drives and has risk of data loss. To avoid the risk, do
not set the bit. This change also avoids failure which happens when the
drives do not support the bit.

Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>

lib/zbc_scsi.c

@@ -991,9 +991,8 @@ int zbc_scsi_flush(struct zbc_device *dev)
 	if (ret != 0)
 		return ret;
 
-	/* Fill command CDB (immediate flush) */
+	/* Fill command CDB */
 	cmd.cdb[0] = ZBC_SG_SYNC_CACHE_CDB_OPCODE;
-	cmd.cdb[1] = 0x02;
 	zbc_sg_set_int64(&cmd.cdb[2], 0);
 	zbc_sg_set_int32(&cmd.cdb[10], 0);