net: ethernet: mtk_wed: Fix NULL vs IS_ERR() bug in mtk_wed_get_memory_region()

We recently changed this from using devm_ioremap() to using
devm_ioremap_resource() and unfortunately the former returns NULL while
the latter returns error pointers. The check for errors needs to be
updated as well.

Fixes: e27dba1951ce ("net: Use of_reserved_mem_region_to_resource{_byname}() for "memory-region"")
Signed-off-by: Dan Carpenter <[e-mail]>
Acked-by: Lorenzo Bianconi <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/ethernet/mediatek/mtk_wed_mcu.c

···
 	region->phy_addr = res.start;
 	region->size = resource_size(&res);
 	region->addr = devm_ioremap_resource(hw->dev, &res);
+	if (IS_ERR(region->addr))
+		return PTR_ERR(region->addr);
 
-	return !region->addr ? -EINVAL : 0;
+	return 0;
 }
 
 static int