x86, microcode: Correct sysdev_add error path

When we encounter an error while initting the microcode driver on a CPU,
we must undo the previously added sysfs group.

Cc: Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
Signed-off-by: NBorislav Petkov <borislav.petkov@amd.com>
Acked-by: NAndreas Herrmann <Andreas.Herrmann3@amd.com>

arch/x86/kernel/microcode_core.c

@@ -417,8 +417,10 @@ static int mc_sysdev_add(struct sys_device *sys_dev)
 	if (err)
 		return err;
 
-	if (microcode_init_cpu(cpu) == UCODE_ERROR)
-		err = -EINVAL;
+	if (microcode_init_cpu(cpu) == UCODE_ERROR) {
+		sysfs_remove_group(&sys_dev->kobj, &mc_attr_group);
+		return -EINVAL;
+	}
 
 	return err;
 }