arm: dts: vt8500: Update Wondermedia SoC dtsi files for pinctrl driver

This patch adds pinctrl nodes to the VIA VT8500 and Wondermedia SoC dtsi
files to support the pinctrl driver.

Signed-off-by: Tony Prisk <linux@prisktech.co.nz>
Acked-by: Linus Walleij <linus.walleij@linaro.org>