ARM: dts: lpc4357-ea4357: add emc pins and static memory devices

Setup the emc pins used by external memory devices and add
configuration for the devices found on the EA4357 devkit.

The EA4357 devkit has a NOR Flash attached to chip select 0
and a D-type flip-flop used for LEDs on chip select 2.

Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Olof Johansson <olof@lixom.net>