Add plat-sunxi

Initial version support for Allwinner A80 platform.
Allwinner A80 is big.little archtecture with 4*A7 + 4*A15,
Support Trustzone tech and secureboot inside hardware.
plat-sunxi support features:
1.Clone plat-sunxi from plat-vexpress;
2.Secure bootloader reserved 64MB secure DRAM for optee_os;
3.Support SMP secondary cpu secure stage bootup;
4.Add uart driver to core/driver/*;
5.Support GIC driver initialization.
The porting work test on Optimus board, with allwinner A80 chip.

Signed-off-by: sunny <sunny@allwinnertech.com>
Fix plat-* core_bootcfg.c message error

The error message for TA_RAM and NSEC_SHM memory is not correct,
Fix it to let the debug message information match with its propose.

Signed-off-by: sunny <sunny@allwinnertech.com>