platform/x86: x86-android-tablets: use swnode_group instead of manual registering

platform/x86: x86-android-tablets: use swnode_group instead of manual registering

Replace manually calling software_node_register_node_group() from init()
with the new swnode_group registration mechanism.

Note this also fixes a missing software_node_unregister_node_group()
for lenovo_yt3_swnodes.

Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Hans de Goede <hansg@kernel.org>
Link: https://patch.msgid.link/20250920200713.20193-14-hansg@kernel.org
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>