hw: Initialise all IDT vectors to "no service"

Initialise all 48 IDT vectors, including those used by hardware
interrupts, to the "no service" routine. This lets us enable i8254
interrupts early.

platform/hw/arch/x86/x86_subr.c

@@ -54,7 +54,7 @@ bmk_x86_initidt(void)
 {
 	int i;
 
-	for (i = 0; i < 32; i++) {
+	for (i = 0; i < 48; i++) {
 		bmk_x86_fillgate(i, bmk_cpu_insr, 0);
 	}