watchdog: sirfsoc: allow setting timeout in devicetree

watchdog_init_timeout() will allways pick timeout_param since it
defaults to a valid timeout.

By following best practice described in
Documentation/watchdog/watchdog-kernel-api.txt, it also
let us to set timout-sec property in devicetree.

Signed-off-by: Marcus Folkesson <[e-mail]>
Reviewed-by: Guenter Roeck <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Signed-off-by: Guenter Roeck <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

Documentation/devicetree/bindings/watchdog/sirfsoc_wdt.txt

···
 - reg: Address range of tick timer/WDT register set
 - interrupts: interrupt number to the cpu
 
+Optional properties:
+- timeout-sec : Contains the watchdog timeout in seconds
+
 Example:
 
 timer@b0020000 {
 	compatible = "sirf,prima2-tick";
 	reg = <0xb0020000 0x1000>;
 	interrupts = <0>;
+	timeout-sec = <30>;
 };

drivers/watchdog/sirfsoc_wdt.c

···
 #define SIRFSOC_WDT_MAX_TIMEOUT		(10 * 60)	/* 10 mins */
 #define SIRFSOC_WDT_DEFAULT_TIMEOUT	30		/* 30 secs */
 
-static unsigned int timeout = SIRFSOC_WDT_DEFAULT_TIMEOUT;
+static unsigned int timeout;
 static bool nowayout = WATCHDOG_NOWAYOUT;
 
 module_param(timeout, uint, 0);