Sync new KVM_CLOCK_CORRECT_TSC_SHIFT from upstream Linux headers.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: qemu/linux-headers/linux/kvm.h
===================================================================
--- qemu.orig/linux-headers/linux/kvm.h
+++ qemu/linux-headers/linux/kvm.h
@@ -1300,6 +1300,9 @@ struct kvm_irqfd {
 #define KVM_CLOCK_TSC_STABLE		2
 #define KVM_CLOCK_REALTIME		(1 << 2)
 #define KVM_CLOCK_HOST_TSC		(1 << 3)
+/* whether tsc_shift as seen by the guest matches guest visible TSC */
+/* This is true since commit 78db6a5037965429c04d708281f35a6e5562d31b */
+#define KVM_CLOCK_CORRECT_TSC_SHIFT	(1 << 4)
 
 struct kvm_clock_data {
 	__u64 clock;