github: add checkpatch action

Add checkpatch.pl invocation for new pull requests. This is using
existing GitHub action from [1].

[1] https://github.com/webispy/checkpatch-action
Signed-off-by: Igor Opaniuk <[email protected]>

Author: igoropaniuk

.checkpatch.conf

@@ -0,0 +1,4 @@
+--no-tree
+--strict
+--ignore FILE_PATH_CHANGES
+--ignore EMAIL_SUBJECT

.github/workflows/checkpatch.yml

@@ -0,0 +1,15 @@
+name: Checkpatch Review
+on: [pull_request]
+jobs:
+  check-patch:
+    name: checkpatch review
+    runs-on: ubuntu-latest
+    steps:
+    - name: 'Calculate PR commits + 1'
+      run: echo "PR_FETCH_DEPTH=$(( ${{ github.event.pull_request.commits }} + 1 ))" >> $GITHUB_ENV
+    - uses: actions/checkout@v3
+      with:
+        ref: ${{ github.event.pull_request.head.sha }}
+        fetch-depth: ${{ env.PR_FETCH_DEPTH }}
+    - name: Run checkpatch review
+      uses: webispy/checkpatch-action@v9