platform/x86: msi-laptop: add missing sysfs_remove_group()

A sysfs group is created in msi_init() when old_ec_model is enabled, but
never removed. Remove the msipf_old_attribute_group in that case.

Fixes: 03696e5 ("msi-laptop: Disable brightness control for new EC")
Signed-off-by: Thomas Fourier <fourier.thomas@gmail.com>
Link: https://patch.msgid.link/20251217103617.27668-2-fourier.thomas@gmail.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Author: Thomas-fourier

drivers/platform/x86/msi-laptop.c

@@ -1130,6 +1130,9 @@ static void __exit msi_cleanup(void)
 	sysfs_remove_group(&msipf_device->dev.kobj, &msipf_attribute_group);
 	if (!quirks->old_ec_model && threeg_exists)
 		device_remove_file(&msipf_device->dev, &dev_attr_threeg);
+	if (quirks->old_ec_model)
+		sysfs_remove_group(&msipf_device->dev.kobj,
+				   &msipf_old_attribute_group);
 	platform_device_unregister(msipf_device);
 	platform_driver_unregister(&msipf_driver);
 	backlight_device_unregister(msibl_device);