mtd: rawnand: lpx32xx: Fix dma_request_chan() error checks

The dma_request_chan() returns error pointer in case of error, while
dma_request_channel() returns NULL in case of error therefore different
error checks are needed for the two.

Fixes: 7326d3fb1ee3 ("mtd: rawnand: lpx32xx: Request DMA channels using DT entries")
Signed-off-by: Piotr Wojtaszczyk <piotr.wojtaszczyk@timesys.com>
Cc: stable@vger.kernel.org
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20240705115139.126522-1-piotr.wojtaszczyk@timesys.com

drivers/mtd/nand/raw/lpc32xx_mlc.c

@@ -575,7 +575,7 @@ static int lpc32xx_dma_setup(struct lpc32xx_nand_host *host)
 	dma_cap_mask_t mask;
 
 	host->dma_chan = dma_request_chan(mtd->dev.parent, "rx-tx");
-	if (!host->dma_chan) {
+	if (IS_ERR(host->dma_chan)) {
 		/* fallback to request using platform data */
 		if (!host->pdata || !host->pdata->dma_filter) {
 			dev_err(mtd->dev.parent, "no DMA platform data\n");

drivers/mtd/nand/raw/lpc32xx_slc.c

@@ -722,7 +722,7 @@ static int lpc32xx_nand_dma_setup(struct lpc32xx_nand_host *host)
 	dma_cap_mask_t mask;
 
 	host->dma_chan = dma_request_chan(mtd->dev.parent, "rx-tx");
-	if (!host->dma_chan) {
+	if (IS_ERR(host->dma_chan)) {
 		/* fallback to request using platform data */
 		if (!host->pdata || !host->pdata->dma_filter) {
 			dev_err(mtd->dev.parent, "no DMA platform data\n");