pinctrl: apple: Add "apple,t8103-pinctrl" compatible

After discussion with the devicetree maintainers we agreed to not extend
lists with the generic compatible "apple,pinctrl" anymore [1]. Use
"apple,t8103-pinctrl" as fallback 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,t8103-pinctrl".

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>
Acked-by: Mark Kettenis <kettenis@openbsd.org>

drivers/pinctrl/pinctrl-apple.c

@@ -192,6 +192,7 @@ static struct pinctrl_ops apple_pinctrl_ops = {
 };
 
 static const struct udevice_id apple_pinctrl_ids[] = {
+	{ .compatible = "apple,t8103-pinctrl" },
 	{ .compatible = "apple,pinctrl" },
 	{ /* sentinel */ }
 };