Platform: Reorganize Corstone300 platforms

* Apply Corstone310 improvements in CS300
* Unification CS310 nad CS300 platforms for
  better maintainability
* Separate FVP and FPGA builds
* Code runs from QSPI

Signed-off-by: Dávid Házi <david.hazi@arm.com>
Change-Id: I06bf37cdffb55d411d523b0635e8ac9c10f3fefa
118 files changed