led_class: fix typo in blink API

When I added led_blink_set I had a typo: the return value of the hw
offload is a regular error code that is zero when succesful, and in that
case software emulation should not be used, rather than the other way
around.

Signed-off-by: Johannes Berg <[e-mail]>
Cc: Richard Purdie <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/leds/led-class.c

···
 		   unsigned long *delay_off)
 {
 	if (led_cdev->blink_set &&
-	    led_cdev->blink_set(led_cdev, delay_on, delay_off))
+	    !led_cdev->blink_set(led_cdev, delay_on, delay_off))
 		return;
 
 	/* blink with 1 Hz as default if nothing specified */