rfkill: some minor kernel-doc changes for rfkill_toggle_radio

Improve rfkill_toggle_radio's kernel-doc header a bit.

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