mpc83xx: Add gazerbeam board

The gdsys gazerbeam board is based on a Freescale MPC8308 SOC.
It boots from NOR-Flash, kernel and rootfs are stored on
SD-Card.

On board peripherals include:
- 2x 10/100 Mbit/s Ethernet (optional)

Signed-off-by: Dirk Eibach <dirk.eibach@gdsys.cc>
Signed-off-by: Mario Six <mario.six@gdsys.cc>