staging: comedi: hwdrv_apci3120: remove void function return statement

Returns at the end of void functions are useless.  Remove this one.
Signed-off-by: Chase Southwood <chase.southwood@gmail.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Cc: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c

@@ -1598,8 +1598,6 @@ static void apci3120_interrupt(int irq, void *d)
 		}
 
 	}
-
-	return;
 }
 
 /*