KVM: Move kvm_spurious_fault to x86.c

The routine kvm_spurious_fault() is an x86 specific routine, so
move it from virt/kvm/kvm_main.c to arch/x86/kvm/x86.c.

Fixes this sparse warning when building on arm64:

  virt/kvm/kvm_main.c:warning: symbol 'kvm_spurious_fault' was not declared. Should it be static?
Signed-off-by: Geoff Levand <geoff@infradead.org>
Signed-off-by: Gleb Natapov <gleb@redhat.com>

arch/x86/kvm/x86.c

@@ -261,6 +261,13 @@ void kvm_set_apic_base(struct kvm_vcpu *vcpu, u64 data)
 }
 EXPORT_SYMBOL_GPL(kvm_set_apic_base);
 
+asmlinkage void kvm_spurious_fault(void)
+{
+	/* Fault while not rebooting.  We want the trace. */
+	BUG();
+}
+EXPORT_SYMBOL_GPL(kvm_spurious_fault);
+
 #define EXCPT_BENIGN		0
 #define EXCPT_CONTRIBUTORY	1
 #define EXCPT_PF		2

virt/kvm/kvm_main.c

@@ -2572,14 +2572,6 @@ static int kvm_cpu_hotplug(struct notifier_block *notifier, unsigned long val,
 	return NOTIFY_OK;
 }
 
-
-asmlinkage void kvm_spurious_fault(void)
-{
-	/* Fault while not rebooting.  We want the trace. */
-	BUG();
-}
-EXPORT_SYMBOL_GPL(kvm_spurious_fault);
-
 static int kvm_reboot(struct notifier_block *notifier, unsigned long val,
 		      void *v)
 {