platform/x86: think-lmi: Use kfree_sensitive instead of kfree

key might contain private part of the key, so better use
kfree_sensitive to free it.

Signed-off-by: Wang Ming <machel@vivo.com>
Link: https://lore.kernel.org/r/20230717101114.18966-1-machel@vivo.com


Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>