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

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: 03696e51d75a ("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>