spi: hisi-kunpeng: Fix error checking

The function debugfs_create_dir returns ERR_PTR if an error occurs,
and the appropriate way to verify for errors is to use the inline
function IS_ERR. The patch will substitute the null-comparison with
IS_ERR.

Suggested-by: Ivan Orlov <ivan.orlov0322@gmail.com
Signed-off-by: Yeqi Fu <asuk4.q@gmail.com
Link: https://lore.kernel.org/r/20230518052515.368978-1-asuk4.q@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org

Author: Yeqi Fu

drivers/spi/spi-hisi-kunpeng.c

@@ -169,7 +169,7 @@ static int hisi_spi_debugfs_init(struct hisi_spi *hs)
 	master = container_of(hs->dev, struct spi_controller, dev);
 	snprintf(name, 32, "hisi_spi%d", master->bus_num);
 	hs->debugfs = debugfs_create_dir(name, NULL);
-	if (!hs->debugfs)
+	if (IS_ERR(hs->debugfs))
 		return -ENOMEM;
 
 	hs->regset.regs = hisi_spi_regs;