serial: stm32: use the defined variable to simplify code

Use the defined variable 'dev' to make the code cleaner.

Signed-off-by: Zhang Shengju <[e-mail]>
Signed-off-by: Tang Bin <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/serial/stm32-usart.c

···
 	if (uart_console(port))
 		return -ENODEV;
 
-	stm32port->rx_buf = dma_alloc_coherent(&pdev->dev, RX_BUF_L,
+	stm32port->rx_buf = dma_alloc_coherent(dev, RX_BUF_L,
 					       &stm32port->rx_dma_buf,
 					       GFP_KERNEL);
 	if (!stm32port->rx_buf)
···
 
 	stm32port->tx_dma_busy = false;
 
-	stm32port->tx_buf = dma_alloc_coherent(&pdev->dev, TX_BUF_L,
+	stm32port->tx_buf = dma_alloc_coherent(dev, TX_BUF_L,
 					       &stm32port->tx_dma_buf,
 					       GFP_KERNEL);
 	if (!stm32port->tx_buf)