rfkill: Add the capability to switch all devices of all type in __rfkill_switch_all().

__rfkill_switch_all() switches the state of devices of a given type; however,
it does not switch devices of all type (RFKILL_TYPE_ALL). As a result, it
ignores the keycode "KEY_RFKILL" from another module, i.e. eeepc-wmi.

This fix is to make __rfkill_switch_all() to be able to switch not only
devices of a given type but also all devices.

Signed-off-by: Alex Hung <alex.hung@canonical.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>