Don't assume APIC for boot processor has an APIC ID of zero

Originally from Stuart Hayes.

When setting up the APIC for the Uniprocessor kernel don't
assume the CPU has an APIC ID of zero.

This fixes boot with the UP kernel on Dell PowerEdge 6800/6850 4way systems.

Cc: Stuart.Hayes@dell.com

Signed-off-by: Andi Kleen <ak@suse.de>

Index: linux/arch/x86_64/kernel/apic.c
===================================================================
--- linux.orig/arch/x86_64/kernel/apic.c
+++ linux/arch/x86_64/kernel/apic.c
@@ -1051,7 +1051,7 @@ int __init APIC_init_uniprocessor (void)
 
 	connect_bsp_APIC();
 
-	phys_cpu_present_map = physid_mask_of_physid(0);
+	phys_cpu_present_map = physid_mask_of_physid(boot_cpu_id);
 	apic_write_around(APIC_ID, boot_cpu_id);
 
 	setup_local_APIC();