x86: zImage: Pass working device tree data to the kernel

x86: zImage: Pass working device tree data to the kernel

On x86 platforms, U-Boot does not pass Device Tree data to the kernel.
This prevents the kernel from using FDT loaded by U-Boot.

Read the working FDT address from the "fdtaddr" environment variable
and add a copy of the FDT data to the kernel setup_data list.

Signed-off-by: Ivan Gorinov <ivan.gorinov@intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
[bmeng: add #include <linux/libfdt.h> to zimage.c to fix build error]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>