platform/x86: ideapad-laptop: add fn_lock_get/set functions

The FnLock is retrieved and set in several places in the code.

Move details into ideapad_fn_lock_get and ideapad_fn_lock_set functions.

Signed-off-by: Gergo Koteles <soyer@irl.hu>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/dfd3a62a2b71339bbddf01e8a2ccd5ca92ce7202.1712063200.git.soyer@irl.hu


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