tools headers UAPI: Sync x86's asm/kvm.h with the kernel sources

To pick the changes in:

  828ca896 ("KVM: x86: Expose TSC offset controls to userspace")

That just rebuilds kvm-stat.c on x86, no change in functionality.

This silences these perf build warning:

  Warning: Kernel ABI header at 'tools/arch/x86/include/uapi/asm/kvm.h' differs from latest version at 'arch/x86/include/uapi/asm/kvm.h'
  diff -u tools/arch/x86/include/uapi/asm/kvm.h arch/x86/include/uapi/asm/kvm.h

Cc: Oliver Upton <oupton@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/arch/x86/include/uapi/asm/kvm.h

@@ -504,4 +504,8 @@ struct kvm_pmu_event_filter {
 #define KVM_PMU_EVENT_ALLOW 0
 #define KVM_PMU_EVENT_DENY 1
 
+/* for KVM_{GET,SET,HAS}_DEVICE_ATTR */
+#define KVM_VCPU_TSC_CTRL 0 /* control group for the timestamp counter (TSC) */
+#define   KVM_VCPU_TSC_OFFSET 0 /* attribute for the TSC offset */
+
 #endif /* _ASM_X86_KVM_H */