ACPI: Cleanup custom_method debug stuff

- Move param aml_debug_output to other params into sysfs.c
- Split acpi_debugfs_init to prepare custom_method to be
  an own .config option and driver.

Signed-off-by: Thomas Renninger <trenn@suse.de>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: rui.zhang@intel.com
Signed-off-by: Len Brown <len.brown@intel.com>