panasonic-laptop - switch to using sparse keymap library

nstead of implementing its own version of keymap hanlding switch over to
using sparse keymap library.

Cc: Harald Welte <laforge@gnumonks.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Matthew Garrett <mjg@redhat.com>
diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 0b11b41..c0446d6 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -171,6 +171,7 @@
 	tristate "Panasonic Laptop Extras"
 	depends on INPUT && ACPI
 	depends on BACKLIGHT_CLASS_DEVICE
+	select INPUT_SPARSEKMAP
 	---help---
 	  This driver adds support for access to backlight control and hotkeys
 	  on Panasonic Let's Note laptops.