firmware: dmi-id: add a release callback function

dmi_class uses kfree() as the .release function, but that now causes
a warning with clang-16 as it violates control flow integrity (KCFI)
rules:

drivers/firmware/dmi-id.c:174:17: error: cast from 'void (*)(const void *)' to 'void (*)(struct device *)' converts to incompatible function type [-Werror,-Wcast-function-type-strict]
  174 |         .dev_release = (void(*)(struct device *)) kfree,

Add an explicit function to call kfree() instead.

Fixes: 4f5c791 ("DMI-based module autoloading")
Link: https://lore.kernel.org/lkml/20240213100238.456912-1-arnd@kernel.org/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jean Delvare <jdelvare@suse.de>

Author: arndb

drivers/firmware/dmi-id.c

@@ -169,9 +169,14 @@ static int dmi_dev_uevent(const struct device *dev, struct kobj_uevent_env *env)
 	return 0;
 }
 
+static void dmi_dev_release(struct device *dev)
+{
+	kfree(dev);
+}
+
 static struct class dmi_class = {
 	.name = "dmi",
-	.dev_release = (void(*)(struct device *)) kfree,
+	.dev_release = dmi_dev_release,
 	.dev_uevent = dmi_dev_uevent,
 };