hw/i386/x86: Reduce init_topo_info() scope

hw/i386/x86: Reduce init_topo_info() scope

This function is not used anywhere outside this file, so
we can delete the prototype from include/hw/i386/x86.h and
make the function "static void".

This fixes when building with -Wall and using Clang
("Apple clang version 14.0.0 (clang-1400.0.29.202)"):

  ../hw/i386/x86.c:70:24: error: static function 'MACHINE' is used in an inline function with external linkage [-Werror,-Wstatic-in-inline]
      MachineState *ms = MACHINE(x86ms);
                         ^
  include/hw/i386/x86.h:101:1: note: use 'static' to give inline function 'init_topo_info' internal linkage
  void init_topo_info(X86CPUTopoInfo *topo_info, const X86MachineState *x86ms);
  ^
  static
  include/hw/boards.h:24:49: note: 'MACHINE' declared here
  OBJECT_DECLARE_TYPE(MachineState, MachineClass, MACHINE)
                                                  ^

Reported-by: Stefan Weil <sw@weilnetz.de>
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20221216220158.6317-6-philmd@linaro.org>