x86, tools: Fix up compiler warnings

The kbuild test robot reported the following errors that were introduced
with commit 993c30a0 ("x86, tools: Consolidate #ifdef code"),

  arch/x86/boot/tools/build.c: In function 'update_pecoff_setup_and_reloc':
>> arch/x86/boot/tools/build.c:252:1: error: parameter name omitted
    static inline void update_pecoff_setup_and_reloc(unsigned int) {}
    ^
  arch/x86/boot/tools/build.c: In function 'update_pecoff_text':
>> arch/x86/boot/tools/build.c:253:1: error: parameter name omitted
    static inline void update_pecoff_text(unsigned int, unsigned int) {}
    ^
>> arch/x86/boot/tools/build.c:253:1: error: parameter name omitted

   arch/x86/boot/tools/build.c: In function 'main':
>> arch/x86/boot/tools/build.c:372:2: warning: implicit declaration of function 'efi_stub_entry_update' [-Wimplicit-function-declaration]
    efi_stub_entry_update();
    ^
Signed-off-by: Matt Fleming <matt.fleming@intel.com>