[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/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 4924d387..3c684ef 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -159,6 +159,11 @@
 
 	acpi_fake_ecdt	[HW,ACPI] Workaround failure due to BIOS lacking ECDT
 
+	acpi_generic_hotkey [HW,ACPI]
+			Allow consolidated generic hotkey driver to
+			over-ride platform specific driver.
+			See also Documentation/acpi-hotkey.txt.
+
 	ad1816=		[HW,OSS]
 			Format: <io>,<irq>,<dma>,<dma2>
 			See also Documentation/sound/oss/AD1816.