tools headers UAPI: Sync KVM's vmx.h header with the kernel sources

To pick the changes in:

  bf0cd88c

 ("KVM: x86: emulate wait-for-SIPI and SIPI-VMExit")

That makes 'perf kvm-stat' aware of this new SIPI_SIGNAL exit reason,
thus addressing the following perf build warning:

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

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Yadong Qi <yadong.qi@intel.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>