Fix IOAPIC initialisation

In the woolding of the IOAPIC registers, I used incorrect registers
somewhere. Plain incorrect.

After that was fixed, I kept getting 0x22 interrupts, don't know from where.
Internet says, the IRQ line 2 is for cascaded signals from lines 8 - 15?

Anyway, I only enable keyboard and LAPIC timer now - and the latter just for
testing purposes. We have two nice visual counters now. One is the number of
keystrokes (mod 10) and the other's ASCII value is the number of LAPIC timer
interrupts (mod 256).

I didn't bother to remove the traces of the still-local SMP init code this
time. The source won't assemble but that's not my problem.