uboot-phytec

* Get (mostly) rid of CFG_MONITOR_LEN definition; compute real length
  instead CFG_MONITOR_LEN is now only used to determine  _at_compile_
  _time_  (!) if the environment is embedded within the U-Boot image,
  or in a separate flash sector.

* Cleanup CFG_DER #defines in config files (wd maintained only)