sata_promise: fix irq clearing buglets

This patch fixes two bugs in sata_promise's irq status clearing paths:
1. When clearing the irq status for a specific port, the driver
   read the global SEQMASK register. This is wrong because that
   clears the irq status for _all_ ports.
2. pdc_thaw() incorrectly added the PDC_INT_SEQMASK host register
   offset to a per-port ata engine base address. This resulted in
   it reading the unrelated PDC_PKT_SUBMIT register, which did not
   have the desired irq status clearing effect.

In both cases the fix is to read from the port's Command/Status
register. This also matches what Promise's own driver does.
Signed-off-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/sata_promise.c

@@ -663,7 +663,7 @@ static void pdc_thaw(struct ata_port *ap)
 	u32 tmp;
 
 	/* clear IRQ */
-	readl(mmio + PDC_INT_SEQMASK);
+	readl(mmio + PDC_COMMAND);
 
 	/* turn IRQ back on */
 	tmp = readl(mmio + PDC_CTLSTAT);
@@ -781,10 +781,9 @@ static inline unsigned int pdc_host_intr(struct ata_port *ap,
 
 static void pdc_irq_clear(struct ata_port *ap)
 {
-	struct ata_host *host = ap->host;
-	void __iomem *mmio = host->iomap[PDC_MMIO_BAR];
+	void __iomem *mmio = ap->ioaddr.cmd_addr;
 
-	readl(mmio + PDC_INT_SEQMASK);
+	readl(mmio + PDC_COMMAND);
 }
 
 static irqreturn_t pdc_interrupt(int irq, void *dev_instance)