watchdog/imx_watchdog: do not set WCR_WDW

with WCR_WDW set, the watchdog won't trigger if we bootet linux and idle
around while the watchdog is not triggered. It seems the timer makes
progress very slowly if at all. I managed to remain 20minutes alive
while the timeout was set to 60secs. It reboots within 60secs if I start
a busyloop in userland (something like "while (1) { }").

While I don't see a reason why the WDT should not be running while the
CPU is in idle, I'm dropping this bit.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Stefano Babic <sbabic@denx.de>

drivers/watchdog/imx_watchdog.c

@@ -20,7 +20,6 @@ struct watchdog_regs {
 #define WCR_WDE		0x04	/* WDOG enable */
 #define WCR_WDT		0x08
 #define WCR_SRS		0x10
-#define WCR_WDW		0x80
 #define SET_WCR_WT(x)	(x << 8)
 
 #ifdef CONFIG_IMX_WATCHDOG
@@ -47,7 +46,7 @@ void hw_watchdog_init(void)
 #endif
 	timeout = (CONFIG_WATCHDOG_TIMEOUT_MSECS / 500) - 1;
 	writew(WCR_WDZST | WCR_WDBG | WCR_WDE | WCR_WDT | WCR_SRS |
-		WCR_WDW | SET_WCR_WT(timeout), &wdog->wcr);
+		SET_WCR_WT(timeout), &wdog->wcr);
 	hw_watchdog_reset();
 }
 #endif