hw/xtensa: fix reset value of MIROUT register of MX PIC

MX PIC comes out of reset with IRQ routing registers set to 0, thus
not delivering any external IRQ to any connected CPU by default.
Fix the model to match the hardware.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

hw/xtensa/mx_pic.c

@@ -334,7 +334,7 @@ void xtensa_mx_pic_reset(void *opaque)
     mx->miasg = 0;
     mx->mipipart = 0;
     for (i = 0; i < mx->n_irq; ++i) {
-        mx->mirout[i] = 1;
+        mx->mirout[i] = 0;
     }
     for (i = 0; i < mx->n_cpu; ++i) {
         mx->cpu[i].mipicause = 0;