Merge changes from topic "rdevans" into integration

* changes:
  doc: Update list of supported FVP platforms
  board/rdn2: add board support for rdn2 platform
  plat/arm/sgi: adapt to changes in memory map
  plat/arm/sgi: add platform id value for rdn2 platform
  plat/arm/sgi: platform definitions for upcoming platforms
  plat/arm/sgi: refactor header file inclusions
  plat/arm/sgi: refactor the inclusion of memory mapping