rt2x00: Fix radio LED type check

Since "rt2x00: Fix LED state handling", rt2x00leds_led_radio wrongly
checks that the LED type is LED_TYPE_ASSOC. This patch makes it check
for LED_TYPE_RADIO once again.

Signed-off-by: Andrew Price <andy@andrewprice.me.uk>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>