ARM: dts: AM437x: Add the internal and external clock nodes for rtc

rtc can either be supplied from internal 32k clock or external crystal
generated 32k clock. Internal clock is SOC specific and the external
clock is board dependent. Adding the corresponding nodes.

Signed-off-by: Keerthy <j-keerthy@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
diff --git a/arch/arm/boot/dts/am437x-sk-evm.dts b/arch/arm/boot/dts/am437x-sk-evm.dts
index 22af448..7da7c2d 100644
--- a/arch/arm/boot/dts/am437x-sk-evm.dts
+++ b/arch/arm/boot/dts/am437x-sk-evm.dts
@@ -24,6 +24,13 @@
 		display0 = &lcd0;
 	};
 
+	/* fixed 32k external oscillator clock */
+	clk_32k_rtc: clk_32k_rtc {
+		#clock-cells = <0>;
+		compatible = "fixed-clock";
+		clock-frequency = <32768>;
+	};
+
 	backlight {
 		compatible = "pwm-backlight";
 		pwms = <&ecap0 0 50000 PWM_POLARITY_INVERTED>;
@@ -697,6 +704,8 @@
 };
 
 &rtc {
+	clocks = <&clk_32k_rtc>, <&clk_32768_ck>;
+	clock-names = "ext-clk", "int-clk";
 	status = "okay";
 };