imx6: enable IMX6 watchdog

Signed-off-by: Tim Harvey <tharvey@gateworks.com>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@39643 3c298f89-4303-0410-b956-a3cf2f4a3e73
imx6: update Ventana dts

Update the Ventana device-tree to match upstream:
 - Add IMX6Q/IMX6DL variants for GW54xx/GW53xx/GW52xx/GW51xx
 - align pinctrl with upstream
 - consolidate multiple patches into one

Signed-off-by: Tim Harvey <tharvey@gateworks.com>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@39644 3c298f89-4303-0410-b956-a3cf2f4a3e73