LS102xA is an ARMv7 implementation. This patch is to add
basic support for LS1021ATWR board.
 One DDR controller
 DUART1 is used as the console

For the detail board information, please refer to README.
Signed-off-by: NChen Lu <chen.lu@freescale.com>
Signed-off-by: NYuan Yao <yao.yuan@freescale.com>
Signed-off-by: NAlison Wang <alison.wang@freescale.com>