uboot: (firmwareOdroidC2/C4) don't invoke patch tool, use patches = [] instead

https://github.com/NixOS/nixpkgs/blob/master/pkgs/stdenv/generic/setup.sh#L948
this can do it nicely.

Signed-off-by: Anton Arapov <anton@deadbeef.mx>

pkgs/os-specific/linux/kernel/update-libre.sh

@@ -0,0 +1,33 @@
+#! /usr/bin/env nix-shell
+#! nix-shell -i bash -p nix-prefetch-svn git curl
+set -euo pipefail
+
+nixpkgs="$(git rev-parse --show-toplevel)"
+path="$nixpkgs/pkgs/os-specific/linux/kernel/linux-libre.nix"
+
+old_rev="$(grep -o 'rev = ".*"' "$path" | awk -F'"' '{print $2}')"
+old_sha256="$(grep -o 'sha256 = ".*"' "$path" | awk -F'"' '{print $2}')"
+
+svn_url=https://www.fsfla.org/svn/fsfla/software/linux-libre/releases/branches/
+rev="$(curl -s "$svn_url" | grep -Em 1 -o 'Revision [0-9]+' | awk '{print $2}')"
+
+if [ "$old_rev" = "$rev" ]; then
+    echo "No updates for linux-libre"
+    exit 0
+fi
+
+sha256="$(QUIET=1 nix-prefetch-svn "$svn_url" "$rev" | tail -1)"
+
+if [ "$old_sha256" = "$sha256" ]; then
+    echo "No updates for linux-libre"
+    exit 0
+fi
+
+sed -i -e "s/rev = \".*\"/rev = \"$rev\"/" \
+    -e "s/sha256 = \".*\"/sha256 = \"$sha256\"/" "$path"
+
+if [ -n "${COMMIT-}" ]; then
+    git commit -qm "linux_latest-libre: $old_rev -> $rev" "$path" \
+       $nixpkgs/pkgs/os-specific/linux/kernel/linux-libre.nix
+    echo "Updated linux_latest-libre $old_rev -> $rev"
+fi