Fix IO-APIC vector allocation boundary case - we never want to

allocate FIRST_SYSTEM_VECTOR as an external interrupt. It's unlikely,
but could happen if we have a _ton_ of interrupt sources.

Found by Chuck Ebbert.

arch/i386/kernel/io_apic.c

@@ -1117,7 +1117,7 @@ static int __init assign_irq_vector(int irq)
 	if (current_vector == SYSCALL_VECTOR)
 		goto next;
 
-	if (current_vector > FIRST_SYSTEM_VECTOR) {
+	if (current_vector >= FIRST_SYSTEM_VECTOR) {
 		offset = (offset + 1) & 7;
 		current_vector = FIRST_DEVICE_VECTOR + offset;
 	}