ARM: dts: r7s72100: add rtc clock to device tree

Add the realtime clock functional clock source.
Signed-off-by: NChris Brandt <chris.brandt@renesas.com>
Reviewed-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NSimon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r7s72100.dtsi

@@ -117,6 +117,15 @@
 			clock-output-names = "ostm0", "ostm1";
 		};
 
+		mstp6_clks: mstp6_clks@fcfe042c {
+			#clock-cells = <1>;
+			compatible = "renesas,r7s72100-mstp-clocks", "renesas,cpg-mstp-clocks";
+			reg = <0xfcfe042c 4>;
+			clocks = <&p0_clk>;
+			clock-indices = <R7S72100_CLK_RTC>;
+			clock-output-names = "rtc";
+		};
+
 		mstp7_clks: mstp7_clks@fcfe0430 {
 			#clock-cells = <1>;
 			compatible = "renesas,r7s72100-mstp-clocks", "renesas,cpg-mstp-clocks";

include/dt-bindings/clock/r7s72100-clock.h

@@ -29,6 +29,9 @@
 #define R7S72100_CLK_OSTM0	1
 #define R7S72100_CLK_OSTM1	0
 
+/* MSTP6 */
+#define R7S72100_CLK_RTC	0
+
 /* MSTP7 */
 #define R7S72100_CLK_ETHER	4