LoongArch: Check the return value when creating kobj

Add a check for the return value of kobject_create_and_add(), to ensure
that the kobj allocation succeeds for later use.

Cc: stable@vger.kernel.org
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

arch/loongarch/kernel/env.c

@@ -109,6 +109,8 @@ static int __init boardinfo_init(void)
 	struct kobject *loongson_kobj;
 
 	loongson_kobj = kobject_create_and_add("loongson", firmware_kobj);
+	if (!loongson_kobj)
+		return -ENOMEM;
 
 	return sysfs_create_file(loongson_kobj, &boardinfo_attr.attr);
 }