serial: amba-pl011: prefer dma_mapping_error() over explicit address checking

Check for returned DMA addresses using specialized dma_mapping_error()
helper which is generally recommended for this purpose by
Documentation/core-api/dma-api.rst:

"In some circumstances dma_map_single(), ...
will fail to create a mapping. A driver can check for these errors
by testing the returned DMA address with dma_mapping_error()."

Found via static analysis and this is similar to commit fa0308134d26
("ALSA: memalloc: prefer dma_mapping_error() over explicit address checking")

Fixes: 58ac1b379979 ("ARM: PL011: Fix DMA support")
Cc: stable <[e-mail]>
Signed-off-by: Miaoqian Lin <[e-mail]>
Reviewed-by: Gregory CLEMENT <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/serial/amba-pl011.c

···
 	dmatx->len = count;
 	dmatx->dma = dma_map_single(dma_dev->dev, dmatx->buf, count,
 				    DMA_TO_DEVICE);
-	if (dmatx->dma == DMA_MAPPING_ERROR) {
+	if (dma_mapping_error(dma_dev->dev, dmatx->dma)) {
 		uap->dmatx.queued = false;
 		dev_dbg(uap->port.dev, "unable to map TX DMA\n");
 		return -EBUSY;