Remove pre-built dtc binaries

Since we aren't always using flash-tools on x86_64-linux, using
pre-built dtc and fdtoverlay doesn't always work. We should prefer the
dtc package that we provide with nix over the pre-built ones nvidia
provides.

pkgs/flash-tools/default.nix

@@ -59,6 +59,9 @@ let
       # We should never be flashing upstream's kernel, so just remove it so we get errors if it is used
       #rm -f kernel/Image*
 
+      # Remove pre-built binaries for utilities that we already provide with nix
+      rm -f kernel/{dtc,fdtoverlay}
+
       # Remove the big nv_tegra dir, since its not neede by flash scripts.
       # However, save the needed bsp_version file
       mv nv_tegra/bsp_version .