rfkill: add missing line break

Trivial patch adding a missing line break on
rfkill_claim_show().

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