platform/x86: ideapad: Add Y520-15IKBM and Y720-15IKBM to no_hw_rfkill

Lenovo Y520-15IKBM and Y720-15IKBM are another Lenovo models
without physical radio switch and ideapad-laptop reports it
is hard blocked. Add them into no_hw_rfkill to unlock wireless.

BugLink: https://bugs.launchpad.net/bugs/1723612


Signed-off-by: Ike Panhc <ike.pan@canonical.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>