ARM: dts: OMAP: Add counter-32k nodes

Adds the counter-32k timers nodes present in OMAP2/3/4 devices and
device-tree binding documentation for OMAP counter-32k.

Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Signed-off-by: Benoit Cousson <b-cousson@ti.com>

arch/arm/boot/dts/omap4.dtsi

@@ -95,6 +95,12 @@
 		ranges;
 		ti,hwmods = "l3_main_1", "l3_main_2", "l3_main_3";
 
+		counter32k: counter@4a304000 {
+			compatible = "ti,omap-counter32k";
+			reg = <0x4a304000 0x20>;
+			ti,hwmods = "counter_32k";
+		};
+
 		omap4_pmx_core: pinmux@4a100040 {
 			compatible = "ti,omap4-padconf", "pinctrl-single";
 			reg = <0x4a100040 0x0196>;