[media] staging: lirc: remove return void function

This patch fix checkpath "WARNING: void function return statements are not generally useful".
The removed return were useless in that case.
Signed-off-by: Raphaël Poggi <poggi.raph@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/staging/media/lirc/lirc_imon.c

@@ -482,8 +482,6 @@ static void usb_tx_callback(struct urb *urb)
 	/* notify waiters that write has finished */
 	atomic_set(&context->tx.busy, 0);
 	complete(&context->tx.finished);
-
-	return;
 }
 
 /**
@@ -548,7 +546,6 @@ static void ir_close(void *data)
 	}
 
 	mutex_unlock(&context->ctx_lock);
-	return;
 }
 
 /**
@@ -573,7 +570,6 @@ static void submit_data(struct imon_context *context)
 
 	lirc_buffer_write(context->driver->rbuf, buf);
 	wake_up(&context->driver->rbuf->wait_poll);
-	return;
 }
 
 static inline int tv2int(const struct timeval *a, const struct timeval *b)
@@ -709,8 +705,6 @@ static void usb_rx_callback(struct urb *urb)
 	}
 
 	usb_submit_urb(context->rx_urb, GFP_ATOMIC);
-
-	return;
 }
 
 /**