dt-bindings: rtc: Add bindings for m41t80 and compatibles

The ST M41T80 family of RTC are not trivial devices, document them.
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/rtc/rtc-m41t80.txt

+ST M41T80 family of RTC and compatible
+
+Required properties:
+- compatible: should be one of:
+	"st,m41t62",
+	"st,m41t65",
+	"st,m41t80",
+	"st,m41t81",
+	"st,m41t81s",
+	"st,m41t82",
+	"st,m41t83",
+	"st,m41t84",
+	"st,m41t85",
+	"st,m41t87",
+	"microcrystal,rv4162",
+- reg: I2C bus address of the device
+
+Optional properties:
+- interrupt-parent: phandle for the interrupt controller.
+- interrupts: rtc alarm interrupt.
+- clock-output-names: From common clock binding to override the default output
+                      clock name
+- wakeup-source: Enables wake up of host system on alarm
+
+Example:
+	rtc@68 {
+		compatible = "st,m41t80";
+		reg = <0x68>;
+		interrupt-parent = <&UIC0>;
+		interrupts = <0x9 0x8>;
+	};

Documentation/devicetree/bindings/trivial-devices.txt

@@ -175,8 +175,6 @@ sii,s35390a		2-wire CMOS real-time clock
 silabs,si7020		Relative Humidity and Temperature Sensors
 skyworks,sky81452	Skyworks SKY81452: Six-Channel White LED Driver with Touch Panel Bias Supply
 st,24c256		i2c serial eeprom  (24cxx)
-st,m41t62		Serial real-time clock (RTC) with alarm
-st,m41t80		M41T80 - SERIAL ACCESS RTC WITH ALARMS
 taos,tsl2550		Ambient Light Sensor with SMBUS/Two Wire Serial Interface
 ti,ads7828		8-Channels, 12-bit ADC
 ti,ads7830		8-Channels, 8-bit ADC