spi/topcliff-pch: Delete an unnecessary return statement in two functions

The script "checkpatch.pl" pointed information out like the following.

WARNING: void function return statements are not generally useful

Thus remove such statements here.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-topcliff-pch.c

@@ -915,7 +915,6 @@ static void pch_spi_release_dma(struct pch_spi_data *data)
 		dma_release_channel(dma->chan_rx);
 		dma->chan_rx = NULL;
 	}
-	return;
 }
 
 static void pch_spi_handle_dma(struct pch_spi_data *data, int *bpw)
@@ -1292,7 +1291,6 @@ static void pch_free_dma_buf(struct pch_spi_board_data *board_dat,
 	if (dma->rx_buf_dma)
 		dma_free_coherent(&board_dat->pdev->dev, PCH_BUF_SIZE,
 				  dma->rx_buf_virt, dma->rx_buf_dma);
-	return;
 }
 
 static void pch_alloc_dma_buf(struct pch_spi_board_data *board_dat,