remove special case for mach0

Reference: /n/atom/patch/applied/mach0idle
Date: Sat May 24 06:45:19 CES 2014
Signed-off-by: quanstro@quanstro.net

--- /sys/src/nix/k10/arch.c	Sat May 24 06:45:12 2014
+++ /sys/src/nix/k10/arch.c	Sat May 24 06:45:13 2014
@@ -73,6 +73,5 @@
 void
 idlehands(void)
 {
-	if(m->machno != 0)
-		halt();
+	halt();
 }