watchdog: pnx4008: make use of timeout-secs provided in devicetree

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

Following best practice described in
Documentation/watchdog/watchdog-kernel-api.txt to make use of
the parameter logic.
Signed-off-by: NMarcus Folkesson <marcus.folkesson@gmail.com>
Reviewed-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NWim Van Sebroeck <wim@iguana.be>

drivers/watchdog/pnx4008_wdt.c

@@ -78,7 +78,7 @@
 #define WDOG_COUNTER_RATE 13000000	/*the counter clock is 13 MHz fixed */
 
 static bool nowayout = WATCHDOG_NOWAYOUT;
-static unsigned int heartbeat = DEFAULT_HEARTBEAT;
+static unsigned int heartbeat;
 
 static DEFINE_SPINLOCK(io_lock);
 static void __iomem	*wdt_base;