Setup the emc pins used by external memory devices and add
configuration for the devices found on the Hitex eval board.

The Hitex eval board has a NOR Flash attached to chip select 0
and 512 kB of SRAM on chip select 2.
Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Olof Johansson <olof@lixom.net>