watchdog: orion_wdt: take timeout value in ms

The generic wdt_start API expects to be called with the timeout in
milliseconds. Update the orion_wdt driver to accept a timeout in
milliseconds and use the clock rate specified in the dts to convert the
timeout to an appropriate value for the timer reload register.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 34e78be..9d7f503 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -97,6 +97,7 @@
 config WDT_ORION
 	bool "Orion watchdog timer support"
 	depends on WDT
+	select CLK
 	help
 	   Select this to enable Orion watchdog timer, which can be found on some
 	   Marvell Armada chips.