platform/x86: x86-android-tablets: replace bat_swnode with swnode_group

platform/x86: x86-android-tablets: replace bat_swnode with swnode_group

Now that we are using software-nodes are used in more places it is
useful to have a more generic mechanism to have the core code register
software-nodes.

Replace the bat_swnode registration mechanism with a more generic
swnode_group registration mechanism.

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/20250920200713.20193-13-hansg@kernel.org
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>