arm_gic: Fix read of GICD_ICFGR

The GICD_ICFGR register covers 4 interrupts per byte.
Acked-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NAdam Lackorzynski <adam@os.inf.tu-dresden.de>
Message-id: 1408372255-12358-2-git-send-email-adam@os.inf.tu-dresden.de
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

hw/intc/arm_gic.c

@@ -372,7 +372,7 @@ static uint32_t gic_dist_readb(void *opaque, hwaddr offset)
         }
     } else if (offset < 0xf00) {
         /* Interrupt Configuration.  */
-        irq = (offset - 0xc00) * 2 + GIC_BASE_IRQ;
+        irq = (offset - 0xc00) * 4 + GIC_BASE_IRQ;
         if (irq >= s->num_irq)
             goto bad_reg;
         res = 0;