KVM: Fix include dependency for mmu_notifier

The kvm_host struct can include an mmu_notifier struct but mmu_notifier.h is
not included directly.

Signed-off-by: Eric B Munson <emunson@mgebm.net>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 9fedeb3..c6a2ec9 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -14,6 +14,7 @@
 #include <linux/signal.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
+#include <linux/mmu_notifier.h>
 #include <linux/preempt.h>
 #include <linux/msi.h>
 #include <linux/slab.h>