serial: pch_uart: Update error message for dmaengine_prep_slave_sg() API

Commit 16052827 ("dmaengine/dma_slave:
introduce inline wrappers") changed the code to use the new API, but forgot
to update an error message.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Jiri Kosina <trivial@kernel.org>
Cc: linux-serial@vger.kernel.org
--
v2:
  - New
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/pch_uart.c

@@ -1047,7 +1047,7 @@ static unsigned int dma_handle_tx(struct eg20t_port *priv)
 					priv->sg_tx_p, nent, DMA_MEM_TO_DEV,
 					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 	if (!desc) {
-		dev_err(priv->port.dev, "%s:device_prep_slave_sg Failed\n",
+		dev_err(priv->port.dev, "%s:dmaengine_prep_slave_sg Failed\n",
 			__func__);
 		return 0;
 	}