Lifebook E734/E744/E754 has a radio toggle button which uses code 0x420.
Map it to KEY_RFKILL.
Signed-off-by: NMichał Kępień <kernel@kempniu.pl>
Acked-by: NJonathan Woithe <jwoithe@just42.net>
Signed-off-by: NDarren Hart <dvhart@linux.intel.com>