watchdog: apple: Add "apple,t8103-wdt" compatible

After discussion with the devicetree maintainers we agreed to not extend
lists with the generic compatible "apple,wdt" anymore [1]. Use
"apple,t8103-wdt" as base compatible as it is the SoC driver and
bindings were originally written for.
The t602x (M2 Pro/Max/Ultra) devicetrees submitted in [2] use this
compatible as fallback instead of "apple,wdt".

Link: https://lore.kernel.org/asahi/12ab93b7-1fc2-4ce0-926e-c8141cfe81bf@kernel.org/ [1]
Link: https://lore.kernel.org/asahi/20250828-dt-apple-t6020-v1-0-507ba4c4b98e@jannau.net/ [2]
Signed-off-by: Janne Grunau <j@jannau.net>
Reviewed-by: Stefan Roese <stefan.roese@mailbox.org>
Acked-by: Mark Kettenis <kettenis@openbsd.org>

drivers/watchdog/apple_wdt.c

@@ -78,6 +78,7 @@ static const struct wdt_ops apple_wdt_ops = {
 };
 
 static const struct udevice_id apple_wdt_ids[] = {
+	{ .compatible = "apple,t8103-wdt" },
 	{ .compatible = "apple,wdt" },
 	{ /* sentinel */ }
 };