ACPI: Move acpi_blacklisted() declaration to asm/acpi.h

The function acpi_blacklisted() is defined only when CONFIG_X86 is
enabled and is only used by X86 arch code. To align with its usage and
definition conditions, move its declaration to asm/acpi.h

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
[ rjw: Added empty code line in a header file ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>