[ACPI] re-enable platform-specific hotkey drivers by default

When both platform-specific and generic drivers exist,
enable generic over-ride with "acpi_generic_hotkey".

http://bugzilla.kernel.org/show_bug.cgi?id=4953

Signed-off-by: Luming Yu <luming.yu@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/Documentation/acpi-hotkey.txt b/Documentation/acpi-hotkey.txt
index 4c115a7..0acdc80 100644
--- a/Documentation/acpi-hotkey.txt
+++ b/Documentation/acpi-hotkey.txt
@@ -33,3 +33,6 @@
 attached to /proc/acpi/hotkey/poll_method, which is dnyamically
 created.  Please use command "cat /proc/acpi/hotkey/polling_method" 
 to retrieve it.
+
+Note: Use cmdline "acpi_generic_hotkey" to over-ride
+loading any platform specific drivers.