watchdog: Add watchdog_active() routine

Some watchdog may need to check if watchdog is ACTIVE or not, for example in
their suspend/resume hooks.

This patch adds this routine and changes the core drivers to use it.

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
diff --git a/drivers/watchdog/via_wdt.c b/drivers/watchdog/via_wdt.c
index 5603e31..aa50da3 100644
--- a/drivers/watchdog/via_wdt.c
+++ b/drivers/watchdog/via_wdt.c
@@ -91,7 +91,7 @@
 static void wdt_timer_tick(unsigned long data)
 {
 	if (time_before(jiffies, next_heartbeat) ||
-	   (!test_bit(WDOG_ACTIVE, &wdt_dev.status))) {
+	   (!watchdog_active(&wdt_dev))) {
 		wdt_reset();
 		mod_timer(&timer, jiffies + WDT_HEARTBEAT);
 	} else