ACPI: add ACPI debug attribute in sysfs

Add ACPI debug attributes in sysfs.
/proc/acpi/debug_layer && debug_level are deprecated by
/sys/module/acpi/parameters/debug_layer && debug_level.

NOTE: The operations to them are quite the same.
E.g. if you want to enable ACPI_DB_INFO, ACPI_DB_WARN,
 ACPI_DB_ERROR and disable the others,
#echo 0x13 >/sys/module/acpi/parameters/debug_level is OK,
and a boot option "acpi.debug_level = 0x13" also works.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 1f82ceb..a3a1073 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -86,6 +86,8 @@
 	  As the same functions are duplicated in sysfs interface
 	  and this proc interface will be removed some time later,
 	  it's marked as deprecated.
+	  ( /proc/acpi/debug_layer && debug_level are deprecated by
+	    /sys/module/acpi/parameters/debug_layer && debug_level. )
 
 config ACPI_AC
 	tristate "AC Adapter"