workflow: Fix the PR review CI

Improving checkpatch to function properly, as it earlier did not catch
errors properly. One such incident was brought to light when a missing
SOB went undetected.
Ensure that such errors are caught when the PRs are raised itself.

Signed-off-by: Dhruva Gole <[email protected]>

Author: DhruvaG2000

.github/workflows/checkpatch.yml

@@ -1,6 +1,6 @@
 # This is a basic workflow to help you get started with Actions
 
-name: CI
+name: checkpatch review
 
 # Controls when the workflow will run
 on:
@@ -15,15 +15,16 @@ on:
 
 # A workflow run is made up of one or more jobs that can run sequentially or in parallel
 jobs:
-  # This workflow contains a single job called "build"
-  build:
-    # The type of runner that the job will run on
+  my_review:
+    name: checkpatch review
     runs-on: ubuntu-latest
-
-    # Steps represent a sequence of tasks that will be executed as part of the job
     steps:
-      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
-      - uses: actions/checkout@v3
-      - name: checkpatch.pl PR review
-        uses: webispy/checkpatch-action@v8
+    - name: 'Calculate PR commits + 1'
+      run: echo "PR_FETCH_DEPTH=$(( ${{ 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