watchdog: add timeout-sec property binding

this patchset add the timeout-sec property to the following drivers:
orion_wdt, pnx4008_wdt, s3c2410_wdt and at91sam9_wdt.

The at91sam9_wdt is tested on evk-pr3,
the other drivers are compile tested only.

Signed-off-by: Fabio Porcedda <fabio.porcedda@gmail.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Wolfram Sang <w.sang@pengutronix.de>
Cc: Masanari Iida <standby24x7@gmail.com>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: Andrew Victor <linux@maxim.org.za>
Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

Documentation/devicetree/bindings/watchdog/atmel-wdt.txt

@@ -7,9 +7,13 @@ Required properties:
 - reg: physical base address of the controller and length of memory mapped
   region.
 
+Optional properties:
+- timeout-sec: contains the watchdog timeout in seconds.
+
 Example:
 
 	watchdog@fffffd40 {
 		compatible = "atmel,at91sam9260-wdt";
 		reg = <0xfffffd40 0x10>;
+		timeout-sec = <10>;
 	};

Documentation/devicetree/bindings/watchdog/marvel.txt

@@ -5,10 +5,15 @@ Required Properties:
 - Compatibility : "marvell,orion-wdt"
 - reg		: Address of the timer registers
 
+Optional properties:
+
+- timeout-sec	: Contains the watchdog timeout in seconds
+
 Example:
 
 	wdt@20300 {
 		compatible = "marvell,orion-wdt";
 		reg = <0x20300 0x28>;
+		timeout-sec = <10>;
 		status = "okay";
 	};

Documentation/devicetree/bindings/watchdog/pnx4008-wdt.txt

@@ -5,9 +5,13 @@ Required properties:
 - reg: physical base address of the controller and length of memory mapped
   region.
 
+Optional properties:
+- timeout-sec: contains the watchdog timeout in seconds.
+
 Example:
 
 	watchdog@4003C000 {
 		compatible = "nxp,pnx4008-wdt";
 		reg = <0x4003C000 0x1000>;
+		timeout-sec = <10>;
 	};

Documentation/devicetree/bindings/watchdog/samsung-wdt.txt

@@ -9,3 +9,6 @@ Required properties:
 - reg : base physical address of the controller and length of memory mapped
 	region.
 - interrupts : interrupt number to the cpu.
+
+Optional properties:
+- timeout-sec : contains the watchdog timeout in seconds.