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>

.github/workflows/nixos-manual.yml

@@ -0,0 +1,26 @@
+name: NixOS manual checks
+
+permissions: read-all
+
+on:
+  pull_request_target:
+    branches-ignore:
+      - 'release-**'
+    paths:
+      - 'nixos/**/*.xml'
+      - 'nixos/**/*.md'
+
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+    if: github.repository_owner == 'NixOS'
+    steps:
+    - uses: actions/checkout@v3
+      with:
+        # pull_request_target checks out the base branch by default
+        ref: refs/pull/${{ github.event.pull_request.number }}/merge
+    - uses: cachix/install-nix-action@v17
+    - name: Check DocBook files generated from Markdown are consistent
+      run: |
+        nixos/doc/manual/md-to-db.sh
+        git diff --exit-code