spi: stm32-ospi: Fix NULL vs IS_ERR() bug in stm32_ospi_get_resources()

This code was changed from using devm_ioremap() which returns NULL to
using devm_ioremap_resource() which returns error pointers. Update
the error checking to match.

Fixes: defe01abfb7f ("spi: stm32-ospi: Use of_reserved_mem_region_to_resource() for "memory-region"")
Signed-off-by: Dan Carpenter <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

drivers/spi/spi-stm32-ospi.c

···
 	if (!ret) {
 		ospi->mm_size = resource_size(res);
 		ospi->mm_base = devm_ioremap_resource(dev, res);
-		if (!ospi->mm_base) {
+		if (IS_ERR(ospi->mm_base)) {
 			dev_err(dev, "unable to map memory region: %pR\n", res);
-			ret = -ENOMEM;
+			ret = PTR_ERR(ospi->mm_base);
 			goto err_dma;
 		}