remove commented-out version using slow register

Reference: /n/atom/patch/applied/lapicfast
Date: Thu Mar 27 04:55:10 CET 2014
Signed-off-by: quanstro@quanstro.net

--- /sys/src/nix/k10/lapic.c	Thu Mar 27 04:55:02 2014
+++ /sys/src/nix/k10/lapic.c	Thu Mar 27 04:55:04 2014
@@ -377,9 +377,7 @@
 	Apic *apic;
 	vlong period;
 
-//	apic = &xlapic[(lapicrget(Id)>>24) & 0xff];
 	apic = xlapic + m->apicno;
-
 	ilock(&m->apictimerlock);
 
 	period = apic->max;