watchdog: Fix a couple type issues

* Force the type of the literal `1` passed to nstosbt() to ensure it's a
  64-bit type (or larger).  Otherwise it gets inconveniently typed to
  int, resulting in truncation.
* Use `flsll()` when converting sbt to power-of-2-nanoseconds to fix
  32-bit compatibility.

PR:		292616
Obtained from:	Hewlett Packard Enterprise
Fixes:	26d6617f3 ("watchdog: Convert to using sbintime_t format")
MFC after:	3 days

sys/dev/watchdog/watchdog.c

@@ -110,7 +110,7 @@ wdog_kern_pat(u_int utim)
 	if (utim == WD_TO_NEVER)
 		sbt = 0;
 	else
-		sbt = nstosbt(1 << utim);
+		sbt = nstosbt(1ULL << utim);
 
 	return (wdog_kern_pat_sbt(sbt));
 }
@@ -142,7 +142,7 @@ wdog_kern_pat_sbt(sbintime_t sbt)
 
 	/* legacy uses power-of-2-nanoseconds time. */
 	if (sbt != 0) {
-		pow2ns = flsl(sbttons(sbt));
+		pow2ns = flsll(sbttons(sbt));
 	}
 	if (wd_last_sbt != sbt) {
 		wd_last_u = pow2ns;