add pcf2123 RTC overlay on SPI0.0

Author: Kriechi

arch/arm/boot/dts/pcf2123-clock.dts

@@ -0,0 +1,22 @@
+/dts-v1/;
+/plugin/;
+
+/ {
+    compatible = "brcm,bcm2708";
+    fragment@0 {
+        target = <&spi0>;
+        __overlay__ {
+            spidev@0 {
+                status = "disabled";
+            };
+            rtc-pcf2123@0 {
+                #address-cells = <1>;
+                #size-cells = <0>;
+                compatible = "nxp,rtc-pcf2123";
+                spi-max-frequency = <5000000>;
+                spi-cs-high = <1>;
+                reg = <0>;
+            };
+        };
+    };
+};