Add support for TQM8541/8555 boards, TQM85xx support reworked:

- Support for TQM8541/8555 boards added.
- Complete rework of TQM8540/8560 support.
- Common TQM85xx code now supports all current TQM85xx platforms
  (TQM8540/8541/8555/8560).
- DDR SDRAM size detection added.
- CAS latency default values can be overwritten by setting "serial#"
  to e.g. "ABC0001 casl=25" -> CAS latency 2.5 will be used.
  If problems are detected with this non default CAS latency,
  the defualt values will be used instead.
- FLASH size detection added.
- Moved FCC ethernet driver initialization behind TSEC driver init
  -> TSEC is first device.

Patch by Stefan Roese, 30 Nov 2005