Minor - remove permanent_halt function.

The only caller is now in the 0xf0000 segment - so no need for it.
diff --git a/src/romlayout.S b/src/romlayout.S
index 4e3cdab..96aa836 100644
--- a/src/romlayout.S
+++ b/src/romlayout.S
@@ -403,16 +403,6 @@
 
         .code16gcc
 
-// Shutdown a CPU.  We want this in the 0xf000 section to ensure that
-// the code wont be overwritten with something else.  (Should
-// something spurious wake up the CPU, we want to be sure that the hlt
-// insn will still be present and will shutdown the CPU.)
-        DECLFUNC permanent_halt
-permanent_halt:
-        cli
-1:      hlt
-        jmp 1b
-
         // IRQ trampolines
         .macro IRQ_TRAMPOLINE num
         DECLFUNC irq_trampoline_0x\num
diff --git a/src/smpdetect.c b/src/smpdetect.c
index 0617be4..c54ec57 100644
--- a/src/smpdetect.c
+++ b/src/smpdetect.c
@@ -56,7 +56,8 @@
     "  movw %ax, %ds\n"
     "  lock incl smp_cpus\n"
     // Halt the processor.
-    "  jmp permanent_halt\n"
+    "1:hlt\n"
+    "  jmp 1b\n"
     );
 
 /* find the number of CPUs by launching a SIPI to them */