MX35: add support for woodburn board

MX35: add support for woodburn board

The woodburn board is based on the MX35 SOC.
Support for both external (NOR) and internal
(SD Card) boot mode are added. It uses the
generic SPL framework to implement the internal boot
mode.

The following peripherals are supported:
- Ethernet (FEC)
- SD Card
- NAND (512 MB)
- NOR Flash

In the internal boot mode, a simple imximage header
is generated to set the address in internal RAM
where the SOC must copy the SPL code. The initial setup
is then demanded to the SPL itself.

Signed-off-by: Stefano Babic <sbabic@denx.de>