rtc: mcp795: add devicetree support

Add device tree support to the rtc-mcp795 driver.

Signed-off-by: Emil Bartczak <emilbart@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

Documentation/devicetree/bindings/rtc/maxim,mcp795.txt

@@ -0,0 +1,11 @@
+* Maxim MCP795		SPI Serial Real-Time Clock
+
+Required properties:
+- compatible: Should contain "maxim,mcp795".
+- reg: SPI address for chip
+
+Example:
+	mcp795: rtc@0 {
+		compatible = "maxim,mcp795";
+		reg = <0>;
+	};