Xilinx changes for v2018.11-rc2-v2

FPGA:
- Fix SPL fpga loading from FIT

ARM64:
- Fix gic accesses in EL2/EL1

Xilinx:
- Add dlc20 board support
- Add Versal board support
- Sync defconfigs
- Enable MP via Kconfig
- Add missing efuse node
- Enable CDC for zcu100

cmd:
- Fix kgdb Kconfig dependency