ppc64: xics fix for I/O slot deconfigure, from Linda Xie

arch/ppc64/kernel/xics.c

@@ -267,6 +267,15 @@ void xics_disable_irq(u_int virq)
 		       irq, call_status);
 		return;
 	}
+
+	/* Have to set XIVE to 0xff to be able to remove a slot */
+	call_status = rtas_call(ibm_set_xive, 3, 1, NULL, irq, default_server,
+				0xff);
+	if (call_status != 0) {
+	printk("xics_disable_irq: irq=%x: ibm_set_xive(0xff) returned %lx\n",
+	       irq, call_status);
+		return;
+	}
 }
 
 void xics_end_irq(u_int	irq)