[RFKILL]: Move rfkill_switch_all out of global header

rfkill_switch_all shouldn't be called by drivers directly,
instead they should send a signal over the input device.

To prevent confusion for driver developers, move the
function into a rfkill private header.

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>