watchdog: Clean up defaults for imx_watchdog / ulp_wdog

In imx_watchdog, clean up the comment to just note the range now, as we
do not need to set the default here as Kconfig does this for us. For
ulp_wdog, set the default value via Kconfig instead.

Cc: Stefan Roese <sr@denx.de>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index f1b1cf6..b5ac8f7 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -30,6 +30,7 @@
 	default 128000 if ARCH_MX7 || ARCH_VF610
 	default 30000 if ARCH_SOCFPGA
 	default 16000 if ARCH_SUNXI
+	default 5376 if ULP_WATCHDOG
 	default 60000
 	help
 	  Watchdog timeout in msec