watchdog: move WATCHDOG_TIMEOUT_MSECS to Kconfig

move WATCHDOG_TIMEOUT_MSECS to Kconfig and fix
all board defconfigs.

Signed-off-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Stefan Roese <sr@denx.de>
Acked-by: Lukasz Majewski <lukma@denx.de>
Acked-by: Martyn Welch <martyn.welch@collabora.com>
Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/configs/m53menlo_defconfig b/configs/m53menlo_defconfig
index 5004795..7e5bcf9 100644
--- a/configs/m53menlo_defconfig
+++ b/configs/m53menlo_defconfig
@@ -89,4 +89,5 @@
 CONFIG_SYS_WHITE_ON_BLACK=y
 CONFIG_VIDEO_IPUV3=y
 CONFIG_IMX_WATCHDOG=y
+CONFIG_WATCHDOG_TIMEOUT_MSECS=8000
 CONFIG_FAT_WRITE=y