arm64: dts: m3ulcb: enable EXTALR clk

This enables EXTALR clock that can be used for the watchdog.

Signed-off-by: Vladimir Barinov <vladimir.barinov@cogentembedded.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm64/boot/dts/renesas/r8a7796-m3ulcb.dts

@@ -60,6 +60,10 @@
 	clock-frequency = <16666666>;
 };
 
+&extalr_clk {
+	clock-frequency = <32768>;
+};
+
 &pfc {
 	pinctrl-0 = <&scif_clk_pins>;
 	pinctrl-names = "default";