dtc: import package for dtc & fdt from packages feed

dtc: import package for dtc & fdt from packages feed

fdt* utils are needed by targets that use U-Boot FIT images for
sysupgrade. It includes all recent BCM4908 SoC routers as Broadcom
switched from CFE to U-Boot.

fdtget is required for extracting images (bootfs & rootfs) from
Broadcom's ITB. Extracted images can be then flashed to UBI volumes.

sysupgrade is core functionality so it needs dtc as part of base code
base.

Cc: Yousong Zhou <yszhou4tech@gmail.com>
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>