cciss: do not attempt to read from a write-only register

Most smartarrays will tolerate it, but some new ones don't.
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>

Note: this is a regression caused by commit 1ddd5049
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

drivers/block/cciss.h

@@ -223,7 +223,7 @@ static void SA5_submit_command( ctlr_info_t *h, CommandList_struct *c)
 			h->ctlr, c->busaddr);
 #endif /* CCISS_DEBUG */
          writel(c->busaddr, h->vaddr + SA5_REQUEST_PORT_OFFSET);
-	readl(h->vaddr + SA5_REQUEST_PORT_OFFSET);
+	readl(h->vaddr + SA5_SCRATCHPAD_OFFSET);
 	 h->commands_outstanding++;
 	 if ( h->commands_outstanding > h->max_outstanding)
 		h->max_outstanding = h->commands_outstanding;