uboot-imx

ARM: dts: at91: add dts file for sama5d4ek

Add the device tree file for sama5d4ek board.

The dts file is copied from Linux-4.4, do the following changes.
 - add the "u-boot,dm-pre-reloc" property to determine which nodes
   which are needed by SPL and by the board_init_f stage.
 - fix the compilation warning.

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>