ARM: dts: lpc4350-hitex-eval: add pinctrl and uart0 muxing

Setup pin muxing and properties for the debug console on uart0.

Signed-off-by: Ariel D'Alessandro <ariel@vanguardiasur.com.ar>
Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Olof Johansson <olof@lixom.net>