cm1_qp1 -> cm5200: single U-Boot image for modules from the cm5200 family.

Add the ability for modules from the Schindler cm5200 family to use a
single U-Boot image:
- rename cm1_qp1 to cm5200
- add run-time module detection
- parametrize SDRAM configuration according to the module we are running on

Few minor, board-specific fixes included in this patch:
- better MAC address handling
- updated default environment ('update' command uses +{filesize} now)
- improved error messages in the auto-update code
- allow booting U-Boot from RAM (CFG_RAMBOOT)

Signed-off-by: Grzegorz Bernacki <gjb@semihalf.com>
Signed-off-by: Piotr Kruszynski <ppk@semihalf.com>
Signed-off-by: Bartlomiej Sieka <tur@semihalf.com>