config: add eMAG

config: add eMAG

Add the make and meson based build infrastructure for the eMAG platform
from Ampere Computing corp., which is a 64-bit ARM processor with 32
Armv8 64-bit CPU cores. For more information, refer to:
https://amperecomputing.com/product/

Signed-off-by: Jerry Hao OS <jerryhao@os.amperecomputing.com>
Signed-off-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Reviewed-by: Phil Yang <phil.yang@arm.com>
Acked-by: Jerin Jacob <jerinj@marvell.com>