ACPI / boot: Don't define unused variables

ACPI / boot: Don't define unused variables

Some code in acpi_parse_x2apic() conditionally compiled, though parts of
it are being used in any case. This annoys gcc.

arch/x86/kernel/acpi/boot.c: In function ‘acpi_parse_x2apic’:
arch/x86/kernel/acpi/boot.c:203:5: warning: variable ‘enabled’ set but not used [-Wunused-but-set-variable]
  u8 enabled;
     ^~~~~~~
arch/x86/kernel/acpi/boot.c:202:6: warning: variable ‘apic_id’ set but not used [-Wunused-but-set-variable]
  int apic_id;
      ^~~~~~~

Re-arrange the code to avoid compiling unused variables.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>