rfkill: do not allow userspace to override ALL RADIOS OFF

SW_RFKILL_ALL is the "emergency power-off all radios" input event.  It must
be handled, and must always do the same thing as far as the rfkill system
is concerned: all transmitters are to go *immediately* offline.

For safety, do NOT allow userspace to override EV_SW SW_RFKILL_ALL OFF.  As
long as rfkill-input is loaded, that event will *always* be processed, and
it will *always* force all rfkill switches to disable all wireless
transmitters, regardless of user_claim attribute or anything else.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Cc: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: John W. Linville <linville@tuxdriver.com>