KVM: Simplify coalesced mmio initialization

- add destructor function
- move related allocation into constructor
- add stubs for !CONFIG_KVM_MMIO

Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/virt/kvm/coalesced_mmio.h b/virt/kvm/coalesced_mmio.h
index e703346..8a5959e 100644
--- a/virt/kvm/coalesced_mmio.h
+++ b/virt/kvm/coalesced_mmio.h
@@ -10,6 +10,8 @@
  *
  */
 
+#ifdef CONFIG_KVM_MMIO
+
 #define KVM_COALESCED_MMIO_ZONE_MAX 100
 
 struct kvm_coalesced_mmio_dev {
@@ -21,9 +23,17 @@
 };
 
 int kvm_coalesced_mmio_init(struct kvm *kvm);
+void kvm_coalesced_mmio_free(struct kvm *kvm);
 int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
                                        struct kvm_coalesced_mmio_zone *zone);
 int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
                                          struct kvm_coalesced_mmio_zone *zone);
 
+#else
+
+static inline int kvm_coalesced_mmio_init(struct kvm *kvm) { return 0; }
+static inline void kvm_coalesced_mmio_free(struct kvm *kvm) { }
+
+#endif
+
 #endif