This commit adds devicetree for Hikey960 board. Most of the contents are
copied from Linux kernel with some modifications for u-boot. To be
more precise, SD card's speed related properties are removed due to a
bug in u-boot clock implementation. Hence forcing the SD controller to
work in standard speed.
Signed-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>