tools arch kvm: Sync kvm headers with the kernel sources

To pick up the changes from:

70f094f4f01dc4d6 ("KVM: nVMX: Properly pad 'struct kvm_vmx_nested_state_hdr'")

That don't entail changes in tooling.

This silences these tools/perf build warnings:

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: Paolo Bonzini <[e-mail]>
Cc: Vitaly Kuznetsov <[e-mail]>
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

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

···
 		__u16 flags;
 	} smm;
 
+	__u16 pad;
+
 	__u32 flags;
 	__u64 preemption_timer_deadline;
 };