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 <randy.dunlap@oracle.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Matthew Garrett <mjg@redhat.com>
Cc: platform-driver-x86@vger.kernel.org
Signed-off-by: Matthew Garrett <mjg@redhat.com>