platform/x86: ideapad-laptop: check for touchpad support in _CFG

Bit 30 of _CFG is set if the device has a touchpad, check that
in is_visible() for the touchpad attribute. Show 'touchpad', if
supported, in the list of capabilities in the 'cfg' debugfs file.

Signed-off-by: Barnabás Pőcze <pobrn@protonmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210203215403.290792-21-pobrn@protonmail.com


Signed-off-by: Hans de Goede <hdegoede@redhat.com>