platform/x86: ideapad-laptop depends on INPUT

Most platform/x86 drivers that use INPUT_SPARSEKMAP also depend on INPUT,
so do the same for ideapad-laptop. This fixes a kconfig warning and
subsequent build errors when CONFIG_INPUT is disabled.

warning: (ACER_WMI && ASUS_LAPTOP && DELL_WMI && HP_WMI && PANASONIC_LAPTOP && IDEAPAD_LAPTOP && EEEPC_LAPTOP && EEEPC_WMI && MSI_WMI && TOPSTAR_LAPTOP && ACPI_TOSHIBA) selects INPUT_SPARSEKMAP which has unmet direct dependencies (!S390 && INPUT)

ERROR: "input_free_device" [drivers/platform/x86/ideapad-laptop.ko] undefined!
ERROR: "input_register_device" [drivers/platform/x86/ideapad-laptop.ko] undefined!
ERROR: "sparse_keymap_setup" [drivers/platform/x86/ideapad-laptop.ko] undefined!
ERROR: "input_allocate_device" [drivers/platform/x86/ideapad-laptop.ko] undefined!
ERROR: "input_unregister_device" [drivers/platform/x86/ideapad-laptop.ko] undefined!
ERROR: "sparse_keymap_free" [drivers/platform/x86/ideapad-laptop.ko] undefined!
ERROR: "sparse_keymap_report_event" [drivers/platform/x86/ideapad-laptop.ko] undefined!

Signed-off-by: Randy Dunlap <[e-mail]>
Cc: David Woodhouse <[e-mail]>
Cc: Matthew Garrett <[e-mail]>
Cc: [e-mail]
Signed-off-by: Matthew Garrett <[e-mail]>

drivers/platform/x86/Kconfig

···
 config IDEAPAD_LAPTOP
 	tristate "Lenovo IdeaPad Laptop Extras"
 	depends on ACPI
-	depends on RFKILL
+	depends on RFKILL && INPUT
 	select INPUT_SPARSEKMAP
 	help
 	  This is a driver for the rfkill switches on Lenovo IdeaPad netbooks.