KVM: Remove ptr comparisons to 0

Fix sparse warnings "Using plain integer as NULL pointer"

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index e34e246..c4ad66b 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -398,7 +398,7 @@
 
 static inline int irqchip_in_kernel(struct kvm *kvm)
 {
-	return pic_irqchip(kvm) != 0;
+	return pic_irqchip(kvm) != NULL;
 }
 
 struct descriptor_table {