watchdog: sunxi: 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 <marcus.folkesson@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

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

@@ -6,9 +6,13 @@ Required properties:
                "allwinner,sun6i-a31-wdt"
 - reg : Specifies base physical address and size of the registers.
 
+Optional properties:
+- timeout-sec : Contains the watchdog timeout in seconds
+
 Example:
 
 wdt: watchdog@1c20c90 {
 	compatible = "allwinner,sun4i-a10-wdt";
 	reg = <0x01c20c90 0x10>;
+	timeout-sec = <10>;
 };

drivers/watchdog/sunxi_wdt.c

@@ -39,7 +39,7 @@
 #define DRV_VERSION		"1.0"
 
 static bool nowayout = WATCHDOG_NOWAYOUT;
-static unsigned int timeout = WDT_MAX_TIMEOUT;
+static unsigned int timeout;
 
 /*
  * This structure stores the register offsets for different variants