platform/x86: ideapad-laptop: constify rfkill_ops structure

Add const to rfkill_ops structure as it is only passed as an argument
to the functions rfkill_alloc. This argument is of type const,
so annotate the structure with const.

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>