common: fdt: Remove additional 4k space for fdt allocation

There is no technical reason to add additional 4k space for FDT. This space
is completely unused and just increase memory requirements. This is
problematic on systems with limited memory resources as Xilinx Zynq
CSE/ZynqMP mini and Versal mini configurations.

The patch is removing additional 4k space.

EFI code is using copy_fdt() which copy FDT to different location.
And all boot commands in case of using U-Boot's FDT pointed by
$fdtcontroladdr are copying FDT to different locations by
image_setup_libfdt().
That's why in proper flow none should modified DTB used by U-Boot that's
why there is no need for additional space.

Signed-off-by: Ashok Reddy Soma <ashok.reddy.soma@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Stephen Warren <swarren@nvidia.com>