Add device tree compiler flag as OS_LINUX for building the DT for linux. Bug 3081230 Change-Id: I7b5efc8840988f7afb9bcd2ee7c1c0997d4f8c3a Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com> Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3089477 Reviewed-on: https://git-master.nvidia.com/r/c/linux/kernel-devicetree/+/3164878