scsi: aha1740: Fix an errro handling path in aha1740_probe()

If 'dma_map_single()' fails, the ref counted 'shpnt' will be decremented
twice because 'scsi_host_put()' is called in the if block, and in the error
handling path.

Axe one of these calls.

Link: https://lore.kernel.org/r/20200228215948.7473-1-christophe.jaillet@wanadoo.fr
Fixes: 1dc09e1 ("scsi: aha1740: stop using scsi_unregister")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/aha1740.c

@@ -592,7 +592,6 @@ static int aha1740_probe (struct device *dev)
 					     DMA_BIDIRECTIONAL);
 	if (!host->ecb_dma_addr) {
 		printk (KERN_ERR "aha1740_probe: Couldn't map ECB, giving up\n");
-		scsi_host_put (shpnt);
 		goto err_host_put;
 	}